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+date = '{{ .Date }}'
+draft = true
+title = '{{ replace .File.ContentBaseName "-" " " | title }}'
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content/_index.md

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+---
+# title: Home Page
+weight: 1
+---

content/courses/_index.md

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+---
+# title: Courses
+weight: 2
+---
+
+<!--* [Introduction to Programming in Java](prog-intro/)
+* [Paradgims of Programming](paradgims/)-->

content/courses/paradigms/_index.md

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+---
+title: Paradgims of Programming
+weight: 3
+---
+

content/courses/prog-intro/_index.md

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+---
+title: Introduction to Programming in Java
+weight: 3
+---
+

content/courses/prog-intro/homeworks/_index.md

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+---
+title: Homeworks
+weight: 4
+---

content/courses/prog-intro/homeworks/sum/ParseIntExample.java

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+// ParseIntExample.java
+
+public class ParseIntExample {
+
+    public static void main(String[] args) {
+        String s = "123";
+        int sum = 321;
+        //! sum = sum + s;
+        sum = sum + Integer.parseInt(s);
+        System.out.println(sum);
+    }
+}

content/courses/prog-intro/homeworks/sum/Sum.java

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+// Sum.java
+
+public class Sum {
+    public static void main(String[] args) {
+        System.out.println("number of arguments: " + args.length);
+        
+        int sum = 0;
+        for (String argument : args) {
+            sum = sum + argument;
+            System.out.println(argument);
+            System.out.println(sum);
+        }
+        
+        System.out.println(sum);
+    }
+}
+

content/courses/prog-intro/homeworks/sum/_index.md

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+---
+title: Sum
+weight: 5
+---
+
+# Task
+ 
+1. You need to create a `Sum` class which will sum integers from command line arguments and output the sum to console.
+2. Examples:
+
+    ```sh
+    java Sum 1 2 3
+    ```
+
+    Expected output: `6`.
+
+    ```sh
+    java Sum 1 2 -3
+    ```
+
+    Expected output: `0`.
+
+
+    ```sh
+    java Sum "1 2 3"
+    ```
+
+    Expected output: `6`.
+
+    ```sh
+    java Sum "1 2" " 3"
+    ```
+
+    Expected output: `6`.
+
+    ```sh
+    java Sum " "
+    ```
+
+    Expected output: `0`.
+
+3. Arguments can be:
+    - digits,
+    - signes `+` and `-`,
+    - [space symbols](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Character.html#isWhitespace(char)) 
+
+4. You can assume that `int` type is sufficient for in-between calculations and result.
+5. Before doing the task make sure to read docs for classes [`String`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/String.html) and [`Integer`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Integer.html).
+6. For debugging use [`System.err`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/System.html#err), because it will be ingnored by the testing program.
+
+--- 
+
+# Solution
+
+After reading about [`String`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/String.html), [`Integer`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Integer.html), [`System.err`](https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/System.html#err) we now know about some usefull methods:
+
+- [`Integer.parseInt(String s, int radix)`](https://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#parseInt-java.lang.String-) which parses the string argument as a signed integer in the radix specified by the second argument. So it basically converts a number from the `String` data type to `int`.
+- [`Character.isWhitespace(char ch)`](https://docs.oracle.com/javase/8/docs/api/java/lang/Character.html#isWhitespace-char-) which checks if a character `ch` is a space symbol or not.
+
+Now let's start coding. Firstly let's define the structure of our program. I will be putting the name of the file at the first line comment in a file and its path if its nessesary.
+
+```java
+// Sum.java
+
+public class Sum {
+    public static void main(String[] args) {
+        // ...
+    }
+}
+```
+
+Okay that's done. What do we do next? Let's look at `String[] args` argument to our `main` method. It represents an array of command line arguments which we need to sum. So know we made our task a little bit easier. Now we can just say that we need to find sum of elements of array `args`.
+
+How are we going to do it though? First let's understand what we can do with this array. Let's modify our class a little bit.
+
+```java
+// Sum.java
+
+public class Sum {
+    public static void main(String[] args) {
+        System.out.println(args.length);
+    }
+}
+```
+
+We've added `System.out.println(args.length)` which takes the field `length` from our `args` object and prints it to the console.
+
+Let's try it. First compile our class using 
+
+```sh 
+$ javac Sum.java
+```
+
+And then we can do some manual testing.
+
+```sh
+$ java Sum 1 2 3
+3
+```
+
+We got `3` as an output as expected. We gave our program 3 command line arguments: `1`, `2` and `3`.
+
+Here are all of the examples 
+
+```sh
+$ java Sum 1 2 -3
+3
+```
+
+```sh 
+$ java Sum "1 2 3"
+1
+```
+
+> [!NOTE]
+> Notice, that we got 1 instead of 3. That's because we put our arguments in `""` so this becomes a single string argument.
+
+```sh 
+$ java Sum "1 2" " 3"
+2
+```
+
+```sh
+$ java Sum " "
+1
+```
+
+> [!NOTE]
+> Here program gives us 1 instead of 0, because despite not having any numbers in the arguments a single whitespace is still an argument.
+
+Now let's try not obly to count our arguments but to list them as well. Let's modify our program a little bit more.
+
+```java
+// Sum.java
+
+public class Sum {
+    public static void main(String[] args) {
+        System.out.println("number of arguments: " + args.length);
+        
+        for (String argument : args) {
+            System.out.println(argument);
+        }
+    }
+}
+```
+
+Here I used `for` loop to do printing ***for*** every `String` element in `args`.
+
+Let's try this with our examples. And don't forget to recompile using `javac Sum.java`.
+
+```sh
+$ java Sum 1 2 3
+number of arguments: 3
+1
+2
+3
+```
+
+```sh
+$ java Sum 1 2 -3
+number of arguments: 3
+1
+2
+-3
+```
+
+```sh
+$ java Sum "1 2 3"
+number of arguments: 1
+1 2 3
+```
+
+> [!NOTE]
+> Again, notice only ***one*** string argument. 
+
+
+```sh
+$ java Sum "1 2" " 3"
+number of arguments: 2
+1 2
+ 3
+```
+
+```sh
+$ java Sum " "
+number of arguments: 1
+ 
+```
+
+Okay, now that we know how to ***iterate*** (or do something for every element), we can calculate the *sum* of all the numbers in the `args` array. To do that we need to create a new variable `sum` of *integer* type and assign it the **value** of `0`. Then for every number in `args` we will add it to `sum`, and so by the end of array we will have the sum of all numbers stored in variable `sum`. This is what the code will look like
+
+```java
+// Sum.java
+
+public class Sum {
+    public static void main(String[] args) {
+        System.out.println("number of arguments: " + args.length);
+        
+        int sum = 0;
+        for (String argument : args) {
+            sum = sum + argument;
+            System.out.println(argument);
+            System.out.println(sum);
+        }
+        
+        System.out.println(sum);
+    }
+}
+```
+
+Seems ok. But let's test it.
+
+```sh
+$ javac Sum.java
+Sum.java:9: error: incompatible types: String cannot be converted to int
+            sum = sum + argument;
+                      ^
+1 error
+```
+
+We got a compilation error that says `String cannot be converted to int`. It means that when we try to add 2 variables `sum` and `argument` their types don't match. The type of `sum` is integer and string for `argument`. It seems pretty logical because what do we expect when adding for example `1` and `apple`?..
+
+> [!IMPORTANT]
+> So we need to *cast* `argument` to integer data type so that we can add it to `sum`.
+
+We can do so using [`Integer.parseInt()`](https://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#parseInt-java.lang.String-) method.
+
+It takes a `String s` and returns an `int`, which a string `s` represents. For example this code will work as expected
+
+```java
+// ParseIntExample.java
+
+public class ParseIntExample {
+
+    public static void main(String[] args) {
+        String s = "123";
+        int sum = 321;
+        //! sum = sum + s;
+        sum = sum + Integer.parseInt(s);
+        System.out.println(sum);
+    }
+}
+```
+
+The commented out line (`//!`) would have given us an exception.

content/courses/prog-intro/lectures/_index.md

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+---
+title: Lectures
+weight: 4
+---

content/courses/prog-intro/lectures/intro.md

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+---
+title: Lecture 1. Introduction
+weight: 5
+---
+
+# Why do we choose Java?
+
+According to **TIOBE Programming Community Index** Java is one of the most demanded languages in the programming field.
+
+![TIOBE Programming Community Index](assets/tiobe.png)
+*Img. 1 - TIOBE Programming Community Index*
+
+Also, Java has a lot of advantages for beginners such as:
+
+* It's fairly easy
+* It has a broad spectre of usage
+    * Server
+    * Desktop
+    * Mobile devices
+    * Smart-cards
+
+# What does Java consist of?
+
+Java consists of multiple main components. The first one being the **Java compiler**. The process of converting *human-readable* text to *machine code* is called **compilation**.
+
+![Compilation Process Simplified](assets/compilation-process-simplified.svg) 
+*Img.2 - Simplified Compilation Process*
+
+The behaviour of the Java compiler is described by the [Java Language Specification](https://docs.oracle.com/javase/specs/) or JLS.
+
+Let's talk about compilers a little bit. For example if we will take *C++*. If we take C++ compiler for *x86-64* platform and *Windows* operating system, and launch the compiler on source code it will turn it directly into assembly code.
+
+![C++ code compilation under x86-64](assets/cpp-x86-64-compilation.svg) 
+*Img. X -- C++ code compilation process under x86-64 architecture.*
+
+But what if I want to run my program on *Linux* instead of Windows. I will need to take a different compiler under different operating system and recompile my code using a new compiler. It's not very convenient. 
+
+Java tries to protect us from that. By converting the *Java source code* into *Java byte code*. And then the *byte code* will be ran on the *Java virtual machine* which will run our program on the native processor.
+
+![Java code compilation](assets/java-code-compilation.svg) 
+*Img. X -- Java code compilation*
+
+This approach allows to change only **JVM** according to our platform (*x86_64, ARM, ...*) and operating system (*Windows, MacOS, GNU-Linux, ...*) while *byte code* stays the same. We can only write our code once, than compile it and run under everywhere. 
+
+As the motto says:
+
+> Write once -- ~debug~ run everywhere.
+
+ The third component of Java is the standart library which is included in the JVM. 
+
+There are multiple redactions of Java-platforms:
+
+* Standart edition
+  - *For regular aplications*
+* Enterprise edition
+  - *For server aplications*
+* Micro-edition
+  - *For mobile aplications*
+  - *Isn't in use nowadays 🪦*
+* Java Card
+  - *Sim- and smart-cards*
+
+There also were multiple versions of Java throughout its history.
+
+
+- JDK 1.0 (Jan 1996)
+- J2SE 1.2 (Dec 1998)
+  * *Collections Framework*
+- J2SE 5.0 (Sep 2004)
+  * *Generics*
+- Java SE 8 (Mar 2014)
+  * *Streams and Lambdas*
+- Java SE 9 (Sep 2017)
+  * *Modules*
+- Java SE 10 (Mar 2018)
+  * `var`
+- Java 11 (Sep 2018)
+  * `jshell`
+- Java 17 [LTS-old] (Sep 2021)
+  * *Previous stable version*
+  * *Many little changes*
+- Java 21 [LTS] (Sep 2023)
+  * *Current stable version*
+- Java 25 (Sep 2025)
+  * *Next version*
+
+Java comes in two parts: **JDK - Java Development Kit** and **JVM - Java Virtual Machine**.
+
+There is also a **JRE - Java Runtime Environment**. For example if we want to run our code somewhere on the server we don't need to compile it there because we have our byte code and we just need JRE to run it.
+
+Some of the most popular JVMs right now are:
+
+- OpenJDK
+- Eclipse
+- Azul Systems
+- Excelsior JET
+
+The disadvantage of such system is in the connection between JVM and a native processing unit. In case of C++ compiler that we reviewed earlier the source code is compiled directly into machine-code but in case with Java it is compiled into byte-code. And so the problem is to develop such a JVM that would quickly turn our byte-code into machine-code. Anyway it takes extra time. That's why it mostly will be slower than direct compilation into machine-code. So ultimately while we have the advantage of compiling out code only once, we have the disadvantage of turning byte-code into machine-code slower.
+
+None the less, there is a way to speed up this process which is called JIT - Just In Time compilation. How does it work? While our program is running some of the instructions or functions turns directly into processor commands. 
+
+# What is garbage collection?
+
+For example we have `int` which is represented with 4 bytes of data which is directly stored in memory.
+
+![`int` in memory](assets/int-in-memory.svg)
+*Img. X -- `int` in memory*
+
+But what if we have a `String`. How many memory cells does this string take? We don't know. We will say that our `String` that has length of 5 symbols is stored at `0x12347865`. We defined an address where this string is located in memory. And somewhere in the memory of our programm will be a large buffer where the 5 cells will be stored. 
+
+![`String` in memory](assets/string-in-memory.svg)
+*Img. X -- `String` in memory*
+
+But what do we do with that buffer? We won't need it forever and so sometimes we need to clear that buffer. In case with C/C++ whoever created the memory for that string is in charge of clearing it. There are also languages with garbage collection such as Java and Python. The purpose of the **Garbage Collector** is to automatically find variables that we no longer need and clear their memory.
+
+Suppose we have some code like this.
+
+```java 
+if (someCondition) { 
+    x = [1, 3, 7] // first link 
+    // some code here 
+    y = x // second link 
+    // some code here 
+} // no links
+```
+
+After the `if`-statement we no longer need `x` or `y`. Every variable in this case `x` and `y` is the link to our array (`[1, 3, 7]`). After we left the `if`-statement the amount of links to the array is zero, so we can safely delete the array. This approach is implemented in Python. The problem is that if we have to objects linked to one another and there are no external links, they will not be deleted by garbage collector since there link counter is 1. 
+
+![Edge case for link couting](assets/edge-case-for-link-counting.svg)
+*Img. X -- Edge case for link counting*
+
+The advanced way of implementing the garbage collection is *traversing the graph of links* which is implemented in Java, C# and Go.
+
+# What other advantages does Java have?
+
+- It's easy (in terms of syntax)
+- It's secure and stable
+- It supports Unicode
+- It supports multithreading
+- It has backwards compatibility
+
+# How should Java code look like?
+
+You can go and learn about it [here](https://google.github.io/styleguide/javaguide.html). 
+

content/courses/spring-boot/_index.md

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+---
+# title: Courses
+weight: 3
+---
+
+# Prerequisites
+
+Before diving in, make sure you're comfortable with the following:
+
+- **Java** — solid understanding of the language
+- **Object-oriented programming** — classes, methods and interfaces
+- **Databases** — tables, primary keys, foreign keys, relationships, etc.
+- **SQL** — ability to write basic SQL statements
+
+---
+
+# What is a Spring Framework?
+
+**Spring** is a popular framework for building Java applications. It has a lot of modules, each designed to handle a specific task. They are combined into a few different layers.
+
+![Spring layers](assets/spring-layers.svg)
+*Img. 1 — Spring layers*
+
+| **Layer** | **Purpose** |
+|-----------|-------------|
+| *Core*    | Handling dependency injection, managing objects |
+| *Web*     | Building web applications |
+| *Data*    | Working with databases |
+| *AOP*     | Aspect oriented programming |
+| *Test*    | Testing spring components |
+
+---
+
+While the Spring Framework is powerful, using it often involves a lot of configuration. For example, if you want to build a web app you might need to setup a web server, configure routing and manage dependencies manually. That's when **Spring Boot** comes in.
+
+> [!NOTE]
+> You can think of Spring Boot as a layer on top of the Spring Framework that takes care of all of the setup. *Spring Boot* simplifies Spring development by providing sensible defaults and ready-to-use features.
+
+By the way, the Spring Framework is just one part of a larger family of projects in the **Spring ecosystem**.
+
+![Spring ecosystem](assets/spring-ecosystem.svg)
+*Img. 2 — Spring ecosystem*
+
+| **Module Name**        | **Purpose** |
+|------------------------|-------------|
+| *Spring Data*          | Simplifying database access |
+| *Spring Security*      | Adding authentication and authorization |
+| *Spring Batch*         | Batch processing |
+| *Spring Cloud*         | Building microservices and distributed systems |
+| *Spring Integration*   | Simplifying messaging and integration between systems |
+
+---
+
+# Initialize Spring Boot Project
+
+To initialize a new Spring Boot project, go to [start.spring.io](https://start.spring.io/) and select the options that suit you.
+
+![Spring Options](assets/spring-project-init.png)
+*Img. 3 — Spring Boot options*
+
+After unpacking the `zip` archive, you'll have this template project:
+
+```bash
+.
+├── HELP.md
+├── mvnw
+├── mvnw.cmd
+├── pom.xml
+├── src
+│   ├── main
+│   │   ├── java
+│   │   │   └── tech
+│   │   │       └── codejava
+│   │   │           └── store
+│   │   │               └── StoreApplication.java
+│   │   └── resources
+│   │       └── application.properties
+│   └── test
+│       └── java
+│           └── tech
+│               └── codejava
+│                   └── store
+│                       └── StoreApplicationTests.java
+└── target
+    ├── classes
+    │   ├── application.properties
+    │   └── tech
+    │       └── codejava
+    │           └── store
+    │               └── StoreApplication.class
+    ├── generated-sources
+    │   └── annotations
+    ├── generated-test-sources
+    │   └── test-annotations
+    ├── maven-status
+    │   └── maven-compiler-plugin
+    │       ├── compile
+    │       │   └── default-compile
+    │       │       ├── createdFiles.lst
+    │       │       └── inputFiles.lst
+    │       └── testCompile
+    │           └── default-testCompile
+    │               ├── createdFiles.lst
+    │               └── inputFiles.lst
+    ├── surefire-reports
+    │   ├── TEST-tech.codejava.store.StoreApplicationTests.xml
+    │   └── tech.codejava.store.StoreApplicationTests.txt
+    └── test-classes
+        └── tech
+            └── codejava
+                └── store
+                    └── StoreApplicationTests.class
+```
+
+The "heart" of our project is `pom.xml`:
+
+```xml
+<?xml version="1.0" encoding="UTF-8" ?>
+<project
+    xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"
+>
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>4.0.2</version>
+        <relativePath /> <!-- lookup parent from repository -->
+    </parent>
+    <groupId>tech.codejava</groupId>
+    <artifactId>store</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>store</name>
+    <description>Store</description>
+    <url />
+    <licenses>
+        <license />
+    </licenses>
+    <developers>
+        <developer />
+    </developers>
+    <scm>
+        <connection />
+        <developerConnection />
+        <tag />
+        <url />
+    </scm>
+    <properties>
+        <java.version>21</java.version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>
+```
+
+Maven uses this file to download dependencies and build our project.
+
+In the `src` folder we have the actual code:
+
+```bash
+src
+├── main
+│   ├── java
+│   │   └── tech
+│   │       └── codejava
+│   │           └── store
+│   │               └── StoreApplication.java
+│   └── resources
+│       └── application.properties
+└── test
+    └── java
+        └── tech
+            └── codejava
+                └── store
+                    └── StoreApplicationTests.java
+```
+
+`StoreApplication.java` is the entry point to our application:
+
+```java
+package tech.codejava.store;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class StoreApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(StoreApplication.class, args);
+    }
+
+}
+```
+
+In the `main` method we have a call to `SpringApplication.run`.
+
+Running `mvn clean install` from the root of our project gives us this result *(output partially reduced)*:
+
+```bash
+...
+[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 2.542 s -- in tech.codejava.store.StoreApplicationTests
+[INFO]
+[INFO] Results:
+[INFO]
+[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
+[INFO]
+[INFO]
+[INFO] --- jar:3.4.2:jar (default-jar) @ store ---
+[INFO] Building jar: /home/fymio/store/target/store-0.0.1-SNAPSHOT.jar
+[INFO]
+[INFO] --- spring-boot:4.0.2:repackage (repackage) @ store ---
+...
+[INFO] BUILD SUCCESS
+[INFO] ------------------------------------------------------------------------
+[INFO] Total time:  14.787 s
+[INFO] Finished at: 2026-02-19T13:16:47+03:00
+[INFO] ------------------------------------------------------------------------
+```
+
+Our application built without errors.
+
+---
+
+# Dependency Management
+
+Dependencies are third-party libraries or frameworks we use in our application. For example, to build a web application we need an embedded web server like *Tomcat*, libraries for handling web requests, building APIs, processing JSON data, logging and so on.
+
+In Spring Boot applications, instead of adding multiple individual libraries, we can use a **starter dependency**.
+
+![Spring Boot Starter Web](assets/spring-boot-starter-web.svg)
+*Img. 5 — Spring Boot Starter Web*
+
+To use this dependency, copy the following into your `pom.xml`:
+
+```xml
+<dependency>
+    <groupId>org.springframework.boot</groupId>
+    <artifactId>spring-boot-starter-web</artifactId>
+    <version>4.1.0-M1</version>
+</dependency>
+```
+
+So the `dependencies` section would look like this:
+
+```xml
+<dependencies>
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter</artifactId>
+    </dependency>
+
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-test</artifactId>
+        <scope>test</scope>
+    </dependency>
+
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-web</artifactId>
+        <!-- <version>4.1.0-M1</version> -->
+    </dependency>
+</dependencies>
+```
+
+> [!IMPORTANT]
+> Notice that the version is commented out. It's a better practice to let Spring Boot decide what version of the dependency to use, as it ensures compatibility across your project.
+
+---
+
+# Controllers
+
+**Spring MVC** stands for *Model View Controller*.
+
+- **Model** is where our application's data lives. It represents the business logic and is usually connected to a database or other data sources. In Spring Boot, the model can be a simple Java class.
+- **View** is what the user sees. It's the HTML, CSS or JavaScript rendered in the browser. In Spring MVC, views can be static files or dynamically generated.
+- **Controller** is like a traffic controller. It handles incoming requests from the user, interacts with the model to get data and then tells the view what to display.
+
+Let's add a new Java class called `HomeController` at `src/main/java/tech/codejava/store/HomeController.java`:
+
+```java
+package tech.codejava.store;
+
+public class HomeController {}
+```
+
+To make this a controller, decorate it with the `@Controller` annotation:
+
+```java
+package tech.codejava.store;
+
+import org.springframework.stereotype.Controller;
+
+@Controller
+public class HomeController {}
+```
+
+Now let's add an `index` method. When we send a request to the root of our website, we want this method to be called:
+
+```java
+package tech.codejava.store;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestMapping;
+
+@Controller
+public class HomeController {
+
+    @RequestMapping("/") // this represents the root of our website
+    public String index() {
+        return "index.html"; // this returns the view
+    }
+}
+```
+
+Now we need to create the view. Add `index.html` at `src/main/resources/static/index.html`:
+
+```html
+<!doctype html>
+<html lang="en">
+    <head>
+        <meta charset="UTF-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+        <title>View</title>
+    </head>
+    <body>
+        <h1>Hello world!</h1>
+    </body>
+</html>
+```
+
+Let's build and run our application using `mvn spring-boot:run`. From the logs:
+
+```bash
+2026-02-19T14:55:23.948+03:00  INFO 36752 --- [store] [           main] o.s.boot.tomcat.TomcatWebServer : Tomcat initialized with port 8080 (http)
+```
+
+Our app is up and running at [localhost:8080](http://localhost:8080/).
+
+![Hello world!](assets/hello-world.png)
+*Img. 7 — Our app is up and running!*
+
+---
+
+# Configuring Application Properties
+
+Let's take a look at `src/main/resources/application.properties`:
+
+```properties
+spring.application.name=store
+```
+
+To use this property in our code, we can use the `@Value` annotation. Let's update `HomeController` to print the application name:
+
+```java
+package tech.codejava.store;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.RequestMapping;
+
+@Controller
+public class HomeController {
+
+    @Value("${spring.application.name}")
+    private String appName;
+
+    @RequestMapping("/") // this represents the root of our website
+    public String index() {
+        System.out.println("application name = " + appName);
+        return "index.html"; // this returns the view
+    }
+}
+```
+
+After running the application, we can see `store` printed in the terminal:
+
+```bash
+...
+2026-02-19T15:32:37.507+03:00  INFO 41536 --- [store] [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
+2026-02-19T15:32:37.509+03:00  INFO 41536 --- [store] [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 2 ms
+application name = store
+...
+```
+
+---
+
+# Dependency Injection
+
+Imagine we're building an E-Commerce application that handles placing orders. When an order is placed, the customer's payment needs to be processed — so `OrderService` depends on a payment service like `StripePaymentService`. We can say that `OrderService` is *dependent on* (or *coupled to*) `StripePaymentService`.
+
+![Depends on/Coupled to relation](assets/depends-on-coupled-to.svg)
+*Img. 8 — Depends On/Coupled To relation*
+
+Let's talk about the issues that arise when one class is **tightly coupled** to another.
+
+1. **Inflexibility** — `OrderService` can only use `StripePaymentService`. If tomorrow we decide to switch to a different payment provider like PayPal, we would have to modify `OrderService`. Once we change it, it has to be recompiled and retested, which could impact other classes that depend on it.
+2. **Untestability** — We cannot test `OrderService` in isolation, because `OrderService` is tightly coupled with `StripePaymentService` and we can't test its logic separately from it.
+
+> [!NOTE]
+> The problem here isn't that `OrderService` *depends* on `StripePaymentService` — dependencies are normal in any application. The issue is about *how* the dependency is created and managed.
+
+**Analogy:** Think of a restaurant. A restaurant needs a chef — that's a perfectly normal dependency. If the current chef becomes unavailable, the restaurant can hire another one.
+
+![Restaurant — Chef dependency](assets/restaurant-chef-dependency.svg)
+*Img. X — Restaurant — Chef dependency (Normal)*
+
+Now what if we replace "chef" with a specific person: John? Our restaurant is now dependent on *John specifically*. If John becomes unavailable, we can't replace him — the restaurant is in trouble. This is an example of **tight** or **bad coupling**.
+
+![Restaurant — John dependency](assets/restaurant-john-dependency.svg)
+*Img. X — Restaurant — John dependency (Bad coupling)*
+
+We don't want `OrderService` to be tightly coupled to a specific payment service like Stripe. Instead, we want it to depend on a `PaymentService` *interface*, which could be Stripe, PayPal, or any other provider. To achieve this we can use the *interface* to decouple `OrderService` from `StripePaymentService`.
+
+![Payment Service as `interface`](assets/payment-service-as-interface.svg)
+*Img. X — `PaymentService` as `interface`*
+
+If `OrderService` depends on a `PaymentService` interface, it doesn't know anything about Stripe, PayPal, or any other payment provider. As long as these providers implement `PaymentService`, they can be used to handle payments — and `OrderService` won't care which one is being used.
+
+**Benefits:**
+
+1. If we replace `StripePaymentService` with `PayPalPaymentService`, the `OrderService` class is not affected.
+2. We don't need to modify or recompile `OrderService`.
+3. We can test `OrderService` in isolation, without relying on the specific payment provider like Stripe.
+
+With this setup, we simply give `OrderService` a particular implementation of `PaymentService`. This is called **dependency injection** — we *inject* the dependency into a class.
+
+![Dependency Injection example](assets/dependency-injection.svg)
+*Img. X — Dependency Injection example*
+
+Let's see how it works in our project. Create `OrderService` at `src/main/java/tech/codejava/store/OrderService.java`:
+
+```java
+package tech.codejava.store;
+
+public class OrderService {
+
+    public void placeOrder() {}
+}
+```
+
+> [!NOTE]
+> In a real project we would need to provide something like `Order order` to this method, but for teaching purposes we won't do that.
+
+Now create `StripePaymentService` in the same directory:
+
+```java
+package tech.codejava.store;
+
+public class StripePaymentService {
+
+    public void processPayment(double amount) {
+        System.out.println("=== STRIPE ===");
+        System.out.println("amount: " + amount);
+    }
+}
+```
+
+Let's implement `placeOrder` in `OrderService` using `StripePaymentService`:
+
+```java
+package tech.codejava.store;
+
+public class OrderService {
+
+    public void placeOrder() {
+        var paymentService = new StripePaymentService();
+        paymentService.processPayment(10);
+    }
+}
+```
+
+> [!IMPORTANT]
+> This is our *before* setup — before we introduced the interface. In this implementation, `OrderService` is **tightly coupled** to `StripePaymentService`. We cannot test `OrderService` in isolation, and switching to another payment provider would require modifying `OrderService`.
+
+Let's fix this. Create a `PaymentService` interface in the same directory:
+
+```java
+package tech.codejava.store;
+
+public interface PaymentService {
+    void processPayment(double amount);
+}
+```
+
+Modify `StripePaymentService` to implement `PaymentService`:
+
+```java
+package tech.codejava.store;
+
+public class StripePaymentService implements PaymentService {
+
+    @Override
+    public void processPayment(double amount) {
+        System.out.println("=== STRIPE ===");
+        System.out.println("amount: " + amount);
+    }
+}
+```
+
+The recommended way to inject a dependency into a class is via its **constructor**. Let's define one in `OrderService`:
+
+```java
+package tech.codejava.store;
+
+public class OrderService {
+
+    private PaymentService paymentService;
+
+    public OrderService(PaymentService paymentService) {
+        this.paymentService = paymentService;
+    }
+
+    public void placeOrder() {
+        paymentService.processPayment(10);
+    }
+}
+```
+
+Now let's see this in action. Modify `StoreApplication`:
+
+```java
+package tech.codejava.store;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class StoreApplication {
+
+    public static void main(String[] args) {
+        // SpringApplication.run(StoreApplication.class, args);
+
+        var orderService = new OrderService(new StripePaymentService());
+        orderService.placeOrder();
+    }
+}
+```
+
+Running the application *(output intentionally reduced)*:
+
+```bash
+...
+=== STRIPE ===
+amount: 10.0
+...
+```
+
+Now let's create a `PayPalPaymentService` in the same directory:
+
+```java
+package tech.codejava.store;
+
+public class PayPalPaymentService implements PaymentService {
+
+    @Override
+    public void processPayment(double amount) {
+        System.out.println("=== PayPal ===");
+        System.out.println("amount: " + amount);
+    }
+}
+```
+
+Now we can switch from `StripePaymentService` to `PayPalPaymentService` in `StoreApplication` — without touching `OrderService` at all:
+
+```java
+package tech.codejava.store;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class StoreApplication {
+
+    public static void main(String[] args) {
+        // SpringApplication.run(StoreApplication.class, args);
+
+        // var orderService = new OrderService(new StripePaymentService());
+        var orderService = new OrderService(new PayPalPaymentService());
+        orderService.placeOrder();
+    }
+}
+```
+
+```bash
+...
+=== PayPal ===
+amount: 10.0
+...
+```
+
+Notice that we didn't change `OrderService`. In *object-oriented programming* this is known as the **Open/Closed Principle**:
+
+> A class should be open for extension and closed for modification.
+
+In other words: we should be able to add new functionality to a class without changing its existing code. This reduces the risk of introducing bugs and breaking other parts of the application.
+
+---
+
+## Setter Injection
+
+Another way to inject a dependency is via a **setter**. In `OrderService`, let's define one:
+
+```java
+package tech.codejava.store;
+
+public class OrderService {
+
+    private PaymentService paymentService;
+
+    public void setPaymentService(PaymentService paymentService) {
+        this.paymentService = paymentService;
+    }
+
+    public OrderService(PaymentService paymentService) {
+        this.paymentService = paymentService;
+    }
+
+    public void placeOrder() {
+        paymentService.processPayment(10);
+    }
+}
+```
+
+We can use it like this in `StoreApplication`:
+
+```java
+package tech.codejava.store;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class StoreApplication {
+
+    public static void main(String[] args) {
+        // SpringApplication.run(StoreApplication.class, args);
+
+        // var orderService = new OrderService(new StripePaymentService());
+        var orderService = new OrderService(new PayPalPaymentService());
+        orderService.setPaymentService(new PayPalPaymentService());
+        orderService.placeOrder();
+    }
+}
+```
+
+> [!IMPORTANT]
+> If you remove the constructor from `OrderService` and forget to call the setter, the application will crash with a `NullPointerException`. Use setter injection only for **optional** dependencies — ones that `OrderService` can function without.

go.mod

@@ -0,0 +1,5 @@
+module git.fymio.us/me/codejava.tech
+
+go 1.25.7
+
+require github.com/imfing/hextra v0.11.1 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/imfing/hextra v0.11.1 h1:8pTc4ReYbzGTHAnyiebmlT3ijFfIXiGu1r7tM/UGjFI=
+github.com/imfing/hextra v0.11.1/go.mod h1:cEfel3lU/bSx7lTE/+uuR4GJaphyOyiwNR3PTqFTXpI=

hugo.toml

@@ -0,0 +1,17 @@
+baseURL = 'https://codejava.tech/'
+title = 'CodeJava'
+theme = 'github.com/imfing/hextra'
+
+[menu]
+  [[menu.main]]
+    name = 'Courses'
+    pageRef = '/courses'
+    weight = 1
+  [[menu.main]]
+    name = 'Search'
+    weight = 2
+    [menu.main.params]
+      type = 'search'
+
+[params]
+  description = 'Learn Java programming'

public/404.html

@@ -0,0 +1,40 @@
+<!doctype html>
+<html lang="en">
+  <script src="/livereload.js?mindelay=10&amp;v=2&amp;port=1313&amp;path=livereload" data-no-instant defer></script><body
+    style='font-family:system-ui,"Segoe UI",Roboto,Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji"; height:100vh; text-align:center; display:flex; flex-direction:column; align-items:center; justify-content:center'
+  >
+    <div>
+      <style>
+        body {
+          color: #000;
+          background: #fff;
+          margin: 0;
+        }
+
+        .hextra-error-h1 {
+          border-right: 1px solid rgba(0, 0, 0, 0.3);
+        }
+
+        @media (prefers-color-scheme: dark) {
+          body {
+            color: #fff;
+            background: #000;
+          }
+
+          .hextra-error-h1 {
+            border-right: 1px solid rgba(255, 255, 255, 0.3);
+          }
+        }
+      </style>
+      <h1
+        class="hextra-error-h1"
+        style='display: inline-block; margin: 0 20px 0 0; padding-right: 23px; font-size: 24px; font-weight: 500; vertical-align: top; line-height: 49px; font-feature-settings: "rlig" 1,"calt" 1,"ss01" 1,"ss06" 1 !important;'
+      >
+        404
+      </h1>
+      <div style="display: inline-block; text-align: left">
+        <h2 style="font-size: 14px; font-weight: 400; line-height: 49px; margin: 0">This page could not be found.</h2>
+      </div>
+    </div>
+  </body>
+</html>

public/casts/demo.cast

@@ -0,0 +1,19 @@
+{"version": 2, "width": 80, "height": 24, "timestamp": 1640995200, "env": {"TERM": "xterm-256color", "SHELL": "/bin/bash"}, "title": "Demo Terminal Session"}
+[0.0, "o", "Welcome to the demo!\r\n"]
+[1.0, "o", "$ "]
+[2.0, "o", "ls -la\r\n"]
+[2.5, "o", "total 8\r\n"]
+[2.6, "o", "drwxr-xr-x  2 user user 4096 Jan  1 12:00 .\r\n"]
+[2.7, "o", "drwxr-xr-x 20 user user 4096 Jan  1 12:00 ..\r\n"]
+[2.8, "o", "-rw-r--r--  1 user user    0 Jan  1 12:00 demo.txt\r\n"]
+[3.0, "o", "$ "]
+[4.0, "o", "cat demo.txt\r\n"]
+[4.5, "o", "Hello, this is a demo file!\r\n"]
+[5.0, "o", "$ "]
+[6.0, "o", "echo 'This is a test command'\r\n"]
+[6.5, "o", "This is a test command\r\n"]
+[7.0, "o", "$ "]
+[8.0, "o", "pwd\r\n"]
+[8.5, "o", "/home/user/demo\r\n"]
+[9.0, "o", "$ "]
+[10.0, "o", "exit\r\n"]

public/categories/index.html

@@ -0,0 +1,355 @@
+<!DOCTYPE html>
+<html lang="en" dir="ltr"><head><script src="/livereload.js?mindelay=10&amp;v=2&amp;port=1313&amp;path=livereload" data-no-instant defer></script>
+  <meta charset="utf-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="robots" content="noindex, nofollow" />
+  <link rel="icon shortcut" href="/favicon.ico" sizes="32x32" />
+<link rel="icon" href="/favicon.svg" type="image/svg+xml" id="favicon-svg" />
+<link rel="icon" href="/favicon-16x16.png" type="image/png" sizes="16x16" />
+<link rel="icon" href="/favicon-32x32.png" type="image/png" sizes="32x32" />
+<link rel="apple-touch-icon" href="/apple-touch-icon.png" sizes="180x180" />
+<link fetchpriority="low" href="/site.webmanifest" rel="manifest" />
+<title>Categories – CodeJava</title>
+  <meta name="description" content="" /><link rel="canonical" href="http://localhost:1313/categories/" itemprop="url" />
+
+<meta property="og:title" content="Categories">
+<meta
+  property="og:description"
+  content="
+    
+      Learn Java programming
+    
+  ">
+<meta
+  property="og:type"
+  content="
+    website
+  ">
+<meta property="og:url" content="http://localhost:1313/categories/">
+
+
+  <meta itemprop="name" content="Categories">
+  <meta itemprop="description" content="Learn Java programming">
+  <meta name="twitter:card" content="summary">
+  <meta name="twitter:title" content="Categories">
+  <meta name="twitter:description" content="Learn Java programming">
+<link href="/css/compiled/main.css" rel="stylesheet" />
+    <link href="/css/variables.css" rel="stylesheet" />
+    <link href="/css/custom.css" rel="stylesheet" />
+
+  
+
+
+  <script>
+    
+
+    function setTheme(theme) {
+      document.documentElement.classList.remove("light", "dark");
+
+      if (theme !== "light" && theme !== "dark") {
+       theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+      }
+
+      document.documentElement.classList.add(theme);
+      document.documentElement.style.colorScheme = theme;
+    }
+
+    setTheme("color-theme" in localStorage ? localStorage.getItem("color-theme") : 'system')
+
+  </script>
+
+  <script>
+    
+
+    if (localStorage.getItem('banner-closed')) {
+      document.documentElement.style.setProperty("--hextra-banner-height", "0px");
+      document.documentElement.classList.add("hextra-banner-hidden");
+    }
+  </script>
+
+  
+  
+  </head>
+<body><div class="hextra-nav-container hx:sticky hx:top-0 hx:z-20 hx:w-full hx:bg-transparent hx:print:hidden">
+  <div
+    class="hextra-nav-container-blur hx:pointer-events-none hx:absolute hx:z-[-1] hx:h-full hx:w-full hx:bg-white hx:dark:bg-dark hx:shadow-[0_2px_4px_rgba(0,0,0,.02),0_1px_0_rgba(0,0,0,.06)] hx:contrast-more:shadow-[0_0_0_1px_#000] hx:dark:shadow-[0_-1px_0_rgba(255,255,255,.1)_inset] hx:contrast-more:dark:shadow-[0_0_0_1px_#fff]"
+  ></div>
+
+  <nav class="hextra-max-navbar-width hx:mx-auto hx:flex hx:items-center hx:justify-end hx:gap-2 hx:h-16 hx:px-6">
+    <a class="hx:flex hx:items-center hx:hover:opacity-75 hx:ltr:mr-auto hx:rtl:ml-auto" href="/">
+    <img class="hx:mr-2 hx:block hx:dark:hidden" src="/images/logo.svg" alt="Logo" height="20" width="20" />
+    <img class="hx:mr-2 hx:hidden hx:dark:block" src="/images/logo.svg" alt="Dark Logo" height="20" width="20" />
+    <span class="hx:mr-2 hx:font-extrabold hx:inline hx:select-none" title="CodeJava">CodeJava</span>
+</a>
+<a
+  title=""
+  href="/courses"
+  
+  class="hx:text-sm hx:contrast-more:text-gray-700 hx:contrast-more:dark:text-gray-100 hx:relative hx:-ml-2 hx:hidden hx:whitespace-nowrap hx:p-2 hx:md:inline-flex hx:items-center hx:gap-1 hx:text-gray-600 hx:hover:text-gray-800 hx:dark:text-gray-400 hx:dark:hover:text-gray-200"
+><span class="hx:text-center">Courses</span>
+</a><div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+<button type="button" aria-label="Menu" class="hextra-hamburger-menu hx:cursor-pointer hx:-mr-2 hx:rounded-sm hx:p-2 hx:active:bg-gray-400/20 hx:md:hidden"><svg height=24 fill="none" viewBox="0 0 24 24" stroke="currentColor"><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 8H20"></path></g><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16H20"></path></g></svg></button>
+  </nav>
+</div>
+
+  <div class='hx:mx-auto hx:flex hextra-max-page-width'>
+    <aside class="hextra-sidebar-container hx:flex hx:flex-col hx:print:hidden hx:md:top-16 hx:md:shrink-0 hx:md:w-64 hx:md:self-start hx:max-md:[transform:translate3d(0,-100%,0)] hx:md:hidden hx:xl:block">
+  
+  <div class="hx:px-4 hx:pt-4 hx:md:hidden">
+    <div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+
+  </div>
+  <div class="hextra-scrollbar hx:overflow-y-auto hx:overflow-x-hidden hx:p-4 hx:grow hx:md:h-[calc(100vh-var(--navbar-height)-var(--menu-height))]">
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:md:hidden">
+      
+      
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/"
+    
+  >Courses
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a>
+              
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <div class="hx:max-xl:hidden hx:h-0 hx:w-64 hx:shrink-0"></div></div>
+  
+  
+    <div class="hx:md:hidden  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+  </ul>
+</div></div></div></aside>
+    
+<nav class="hextra-toc hx:order-last hx:hidden hx:w-64 hx:shrink-0 hx:xl:block hx:print:hidden hx:px-4" aria-label="table of contents"></nav>
+
+
+    <article class="hx:w-full hx:break-words hx:flex hx:min-h-[calc(100vh-var(--navbar-height))] hx:min-w-0 hx:justify-center hx:pb-8 hx:pr-[calc(env(safe-area-inset-right)-1.5rem)]">
+      <main class="hx:w-full hx:min-w-0 hx:max-w-6xl hx:px-6 hx:pt-4 hx:md:px-12">
+        <br class="hx:mt-1.5 hx:text-sm" />
+        <h1 class="hx:text-center hx:mt-2 hx:text-4xl hx:font-bold hx:tracking-tight hx:text-slate-900 hx:dark:text-slate-100">Categories</h1>
+        <div class="hx:mb-16"></div>
+        <div class="content">
+          
+        </div>
+        <div class="hx:grid hx:grid-cols-1 hx:md:grid-cols-2 hx:lg:grid-cols-3 hx:xl:grid-cols-4 hx:gap-4">
+          
+        </div>
+      </main>
+    </article>
+  </div>
+
+      <footer class="hextra-footer hx:bg-gray-100 hx:pb-[env(safe-area-inset-bottom)] hx:dark:bg-neutral-900 hx:print:bg-transparent"><div class="hx:mx-auto hx:flex hx:gap-2 hx:py-2 hx:px-4 hextra-max-footer-width"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+  </ul>
+</div></div><hr class="hx:border-gray-200 hx:dark:border-neutral-800" /><div class="hextra-custom-footer hextra-max-footer-width hx:pl-[max(env(safe-area-inset-left),1.5rem)] hx:pr-[max(env(safe-area-inset-right),1.5rem)] hx:text-gray-600 hx:dark:text-gray-400"></div><div
+      class="hextra-max-footer-width hx:mx-auto hx:flex hx:justify-center hx:py-12 hx:pl-[max(env(safe-area-inset-left),1.5rem)] hx:pr-[max(env(safe-area-inset-right),1.5rem)] hx:text-gray-600 hx:dark:text-gray-400 hx:md:justify-start"
+    >
+      <div class="hx:flex hx:w-full hx:flex-col hx:items-center hx:sm:items-start"><div class="hx:font-semibold"><a class="hx:flex hx:text-sm hx:items-center hx:gap-1 hx:text-current" target="_blank" rel="noopener noreferrer" title="Hextra GitHub Homepage" href="https://github.com/imfing/hextra">
+    <span>Powered by Hextra<svg height=1em class="hx:inline-block hx:ltr:ml-1 hx:rtl:mr-1 hx:align-[-2.5px]" viewBox="0 0 180 180" xmlns="http://www.w3.org/2000/svg" fill="currentColor"><path fill-rule="evenodd" clip-rule="evenodd" d="m 105.50024,22.224647 c -9.59169,-5.537563 -21.40871,-5.537563 -31.000093,0 L 39.054693,42.689119 C 29.463353,48.226675 23.55484,58.460531 23.55484,69.535642 v 40.928918 c 0,11.07542 5.908513,21.3092 15.499853,26.84652 l 35.445453,20.46446 c 9.591313,5.53732 21.408404,5.53732 31.000094,0 l 35.44507,-20.46446 c 9.59131,-5.53732 15.49985,-15.7711 15.49985,-26.84652 V 69.535642 c 0,-11.075111 -5.90854,-21.308967 -15.49985,-26.846523 z M 34.112797,85.737639 c -1.384445,2.397827 -1.384445,5.352099 0,7.749927 l 24.781554,42.922974 c 1.38437,2.39783 3.942853,3.87496 6.711592,3.87496 h 49.563107 c 2.76905,0 5.3273,-1.47713 6.71144,-3.87496 l 24.78194,-42.922974 c 1.38414,-2.397828 1.38414,-5.3521 0,-7.749927 L 121.88049,42.814746 c -1.38414,-2.397828 -3.94239,-3.874964 -6.71144,-3.874964 H 65.605944 c -2.768739,0 -5.327223,1.477059 -6.711592,3.874964 z" style="stroke-width:0.774993" /></svg></span>
+  </a></div></div>
+    </div></footer>
+    
+    <script defer src="/js/main.js" integrity=""></script>
+<script defer src="/js/flexsearch.9f5b5908f93ae86f1ecd4b043b799f580c2d1654e703dd9357d568ac41b2547a.js" integrity="sha256-n1tZCPk66G8ezUsEO3mfWAwtFlTnA92TV9VorEGyVHo=" crossorigin="anonymous"></script>
+        <script defer src="/en.search.js" integrity=""></script>
+  </body>
+</html>

public/categories/index.xml

@@ -0,0 +1,18 @@
+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>CodeJava – Categories</title>
+    <link>http://localhost:1313/categories/</link>
+    <description>Recent content in Categories on CodeJava</description>
+    <generator>Hugo -- gohugo.io</generator>
+    <language>en</language>
+    
+	  <atom:link href="http://localhost:1313/categories/index.xml" rel="self" type="application/rss+xml" />
+    
+    
+      
+        
+      
+    
+    
+  </channel>
+</rss>

public/courses/index.html

@@ -0,0 +1,385 @@
+<!DOCTYPE html>
+<html lang="en" dir="ltr"><head><script src="/livereload.js?mindelay=10&amp;v=2&amp;port=1313&amp;path=livereload" data-no-instant defer></script>
+  <meta charset="utf-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="robots" content="noindex, nofollow" />
+  <link rel="icon shortcut" href="/favicon.ico" sizes="32x32" />
+<link rel="icon" href="/favicon.svg" type="image/svg+xml" id="favicon-svg" />
+<link rel="icon" href="/favicon-16x16.png" type="image/png" sizes="16x16" />
+<link rel="icon" href="/favicon-32x32.png" type="image/png" sizes="32x32" />
+<link rel="apple-touch-icon" href="/apple-touch-icon.png" sizes="180x180" />
+<link fetchpriority="low" href="/site.webmanifest" rel="manifest" />
+<title>CodeJava</title>
+  <meta name="description" content="" /><link rel="canonical" href="http://localhost:1313/courses/" itemprop="url" />
+
+<meta property="og:title" content="">
+<meta
+  property="og:description"
+  content="
+    
+      Learn Java programming
+    
+  ">
+<meta
+  property="og:type"
+  content="
+    website
+  ">
+<meta property="og:url" content="http://localhost:1313/courses/">
+
+
+  <meta itemprop="name" content="CodeJava">
+  <meta itemprop="description" content="Learn Java programming">
+  <meta name="twitter:card" content="summary">
+  <meta name="twitter:title" content="CodeJava">
+  <meta name="twitter:description" content="Learn Java programming">
+<link href="/css/compiled/main.css" rel="stylesheet" />
+    <link href="/css/variables.css" rel="stylesheet" />
+    <link href="/css/custom.css" rel="stylesheet" />
+
+  
+
+
+  <script>
+    
+
+    function setTheme(theme) {
+      document.documentElement.classList.remove("light", "dark");
+
+      if (theme !== "light" && theme !== "dark") {
+       theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+      }
+
+      document.documentElement.classList.add(theme);
+      document.documentElement.style.colorScheme = theme;
+    }
+
+    setTheme("color-theme" in localStorage ? localStorage.getItem("color-theme") : 'system')
+
+  </script>
+
+  <script>
+    
+
+    if (localStorage.getItem('banner-closed')) {
+      document.documentElement.style.setProperty("--hextra-banner-height", "0px");
+      document.documentElement.classList.add("hextra-banner-hidden");
+    }
+  </script>
+
+  
+  
+  </head>
+<body><div class="hextra-nav-container hx:sticky hx:top-0 hx:z-20 hx:w-full hx:bg-transparent hx:print:hidden">
+  <div
+    class="hextra-nav-container-blur hx:pointer-events-none hx:absolute hx:z-[-1] hx:h-full hx:w-full hx:bg-white hx:dark:bg-dark hx:shadow-[0_2px_4px_rgba(0,0,0,.02),0_1px_0_rgba(0,0,0,.06)] hx:contrast-more:shadow-[0_0_0_1px_#000] hx:dark:shadow-[0_-1px_0_rgba(255,255,255,.1)_inset] hx:contrast-more:dark:shadow-[0_0_0_1px_#fff]"
+  ></div>
+
+  <nav class="hextra-max-navbar-width hx:mx-auto hx:flex hx:items-center hx:justify-end hx:gap-2 hx:h-16 hx:px-6">
+    <a class="hx:flex hx:items-center hx:hover:opacity-75 hx:ltr:mr-auto hx:rtl:ml-auto" href="/">
+    <img class="hx:mr-2 hx:block hx:dark:hidden" src="/images/logo.svg" alt="Logo" height="20" width="20" />
+    <img class="hx:mr-2 hx:hidden hx:dark:block" src="/images/logo.svg" alt="Dark Logo" height="20" width="20" />
+    <span class="hx:mr-2 hx:font-extrabold hx:inline hx:select-none" title="CodeJava">CodeJava</span>
+</a>
+<a
+  title=""
+  href="/courses"
+  
+  class="hx:text-sm hx:contrast-more:text-gray-700 hx:contrast-more:dark:text-gray-100 hx:relative hx:-ml-2 hx:hidden hx:whitespace-nowrap hx:p-2 hx:md:inline-flex hx:items-center hx:gap-1 hx:font-medium"
+><span class="hx:text-center">Courses</span>
+</a><div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+<button type="button" aria-label="Menu" class="hextra-hamburger-menu hx:cursor-pointer hx:-mr-2 hx:rounded-sm hx:p-2 hx:active:bg-gray-400/20 hx:md:hidden"><svg height=24 fill="none" viewBox="0 0 24 24" stroke="currentColor"><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 8H20"></path></g><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16H20"></path></g></svg></button>
+  </nav>
+</div>
+
+  <div class='hx:mx-auto hx:flex hextra-max-page-width'>
+    <aside class="hextra-sidebar-container hx:flex hx:flex-col hx:print:hidden hx:md:top-16 hx:md:shrink-0 hx:md:w-64 hx:md:self-start hx:max-md:[transform:translate3d(0,-100%,0)] hx:md:sticky">
+  
+  <div class="hx:px-4 hx:pt-4 hx:md:hidden">
+    <div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+
+  </div>
+  <div class="hextra-scrollbar hx:overflow-y-auto hx:overflow-x-hidden hx:p-4 hx:grow hx:md:h-[calc(100vh-var(--navbar-height)-var(--menu-height))]">
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:md:hidden">
+      
+      
+          <li class="open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/"
+    
+  >Courses
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+  <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a>
+              
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:max-md:hidden">
+        
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a></li>
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div></li>
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a></li>
+        
+      </ul>
+    </div>
+  
+  
+    <div class="  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
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+        &lt;h1&gt;Why do we choose Java?&lt;/h1&gt;&lt;p&gt;According to &lt;strong&gt;TIOBE Programming Community Index&lt;/strong&gt; Java is one of the most demanded languages in the programming field.&lt;/p&gt;
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+&lt;p&gt;Also, Java has a lot of advantages for beginners such as:&lt;/p&gt;
+&lt;ul&gt;
+&lt;li&gt;It&amp;rsquo;s fairly easy&lt;/li&gt;
+&lt;li&gt;It has a broad spectre of usage
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+&lt;li&gt;Server&lt;/li&gt;
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+&lt;h1&gt;What does Java consist of?&lt;/h1&gt;&lt;p&gt;Java consists of multiple main components. The first one being the &lt;strong&gt;Java compiler&lt;/strong&gt;. The process of converting &lt;em&gt;human-readable&lt;/em&gt; text to &lt;em&gt;machine code&lt;/em&gt; is called &lt;strong&gt;compilation&lt;/strong&gt;.&lt;/p&gt;
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+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a>
+              
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+  
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:max-md:hidden">
+        
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a></li>
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div></li>
+          <li class="open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a></li>
+        
+      </ul>
+    </div>
+  
+  
+    <div class="  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
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+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+  
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:max-md:hidden">
+        
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a></li>
+          <li class="open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div></li>
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a></li>
+        
+      </ul>
+    </div>
+  
+  
+    <div class="  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+  </ul>
+</div></div></div></aside>
+    
+<nav class="hextra-toc hx:order-last hx:hidden hx:w-64 hx:shrink-0 hx:xl:block hx:print:hidden hx:px-4" aria-label="table of contents">
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public/courses/prog-intro/homeworks/index.xml

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+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>CodeJava – Homeworks</title>
+    <link>http://localhost:1313/courses/prog-intro/homeworks/</link>
+    <description>Recent content in Homeworks on CodeJava</description>
+    <generator>Hugo -- gohugo.io</generator>
+    <language>en</language>
+    
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public/courses/prog-intro/homeworks/sum/ParseIntExample.java

@@ -0,0 +1,12 @@
+// ParseIntExample.java
+
+public class ParseIntExample {
+
+    public static void main(String[] args) {
+        String s = "123";
+        int sum = 321;
+        //! sum = sum + s;
+        sum = sum + Integer.parseInt(s);
+        System.out.println(sum);
+    }
+}

public/courses/prog-intro/homeworks/sum/Sum.java

@@ -0,0 +1,17 @@
+// Sum.java
+
+public class Sum {
+    public static void main(String[] args) {
+        System.out.println("number of arguments: " + args.length);
+        
+        int sum = 0;
+        for (String argument : args) {
+            sum = sum + argument;
+            System.out.println(argument);
+            System.out.println(sum);
+        }
+        
+        System.out.println(sum);
+    }
+}
+

public/courses/prog-intro/homeworks/sum/index.html

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+<title>Sum – CodeJava</title>
+  <meta name="description" content="Task You need to create a Sum class which will sum integers from command line arguments and output the sum to console.
+Examples:
+java Sum 1 2 3 Expected output: 6.
+java Sum 1 2 -3 Expected output: 0." /><link rel="canonical" href="http://localhost:1313/courses/prog-intro/homeworks/sum/" itemprop="url" />
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+Examples:
+java Sum 1 2 3 Expected output: 6.
+java Sum 1 2 -3 Expected output: 0.">
+  <meta itemprop="wordCount" content="919">
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+  <meta name="twitter:title" content="Sum">
+  <meta name="twitter:description" content="Task You need to create a Sum class which will sum integers from command line arguments and output the sum to console.
+Examples:
+java Sum 1 2 3 Expected output: 6.
+java Sum 1 2 -3 Expected output: 0.">
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+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+  
+    <ul class='hx:flex hx:flex-col hx:gap-1 hx:relative hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:dark:before:bg-neutral-800 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:pr-3 hx:rtl:before:right-0 hx:ltr:ml-3 hx:rtl:mr-3'></ul>
+  
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:max-md:hidden">
+        
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a></li>
+          <li class="open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div></li>
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a></li>
+        
+      </ul>
+    </div>
+  
+  
+    <div class="  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+  </ul>
+</div></div></div></aside>
+    
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+      <main class="hx:w-full hx:min-w-0 hx:max-w-6xl hx:px-6 hx:pt-4 hx:md:px-12">
+        
+        <div class="content">
+          <h1>Sum</h1>
+          <h1>Task</h1><ol>
+<li>
+<p>You need to create a <code>Sum</code> class which will sum integers from command line arguments and output the sum to console.</p>
+</li>
+<li>
+<p>Examples:</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>java Sum <span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span> <span style="color:#ae81ff">3</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Expected output: <code>6</code>.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>java Sum <span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span> -3</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Expected output: <code>0</code>.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>java Sum <span style="color:#e6db74">&#34;1 2 3&#34;</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Expected output: <code>6</code>.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>java Sum <span style="color:#e6db74">&#34;1 2&#34;</span> <span style="color:#e6db74">&#34; 3&#34;</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Expected output: <code>6</code>.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>java Sum <span style="color:#e6db74">&#34; &#34;</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Expected output: <code>0</code>.</p>
+</li>
+<li>
+<p>Arguments can be:</p>
+<ul>
+<li>digits,</li>
+<li>signes <code>+</code> and <code>-</code>,</li>
+<li><a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Character.html#isWhitespace%28char%29"target="_blank" rel="noopener">space symbols</a></li>
+</ul>
+</li>
+<li>
+<p>You can assume that <code>int</code> type is sufficient for in-between calculations and result.</p>
+</li>
+<li>
+<p>Before doing the task make sure to read docs for classes <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/String.html"target="_blank" rel="noopener"><code>String</code></a> and <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Integer.html"target="_blank" rel="noopener"><code>Integer</code></a>.</p>
+</li>
+<li>
+<p>For debugging use <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/System.html#err"target="_blank" rel="noopener"><code>System.err</code></a>, because it will be ingnored by the testing program.</p>
+</li>
+</ol>
+<hr>
+<h1>Solution</h1><p>After reading about <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/String.html"target="_blank" rel="noopener"><code>String</code></a>, <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Integer.html"target="_blank" rel="noopener"><code>Integer</code></a>, <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/System.html#err"target="_blank" rel="noopener"><code>System.err</code></a> we now know about some usefull methods:</p>
+<ul>
+<li><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#parseInt-java.lang.String-"target="_blank" rel="noopener"><code>Integer.parseInt(String s, int radix)</code></a> which parses the string argument as a signed integer in the radix specified by the second argument. So it basically converts a number from the <code>String</code> data type to <code>int</code>.</li>
+<li><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Character.html#isWhitespace-char-"target="_blank" rel="noopener"><code>Character.isWhitespace(char ch)</code></a> which checks if a character <code>ch</code> is a space symbol or not.</li>
+</ul>
+<p>Now let&rsquo;s start coding. Firstly let&rsquo;s define the structure of our program. I will be putting the name of the file at the first line comment in a file and its path if its nessesary.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-java" data-lang="java"><span style="display:flex;"><span><span style="color:#75715e">// Sum.java</span>
+</span></span><span style="display:flex;"><span>
+</span></span><span style="display:flex;"><span><span style="color:#66d9ef">public</span> <span style="color:#66d9ef">class</span> <span style="color:#a6e22e">Sum</span> {
+</span></span><span style="display:flex;"><span>    <span style="color:#66d9ef">public</span> <span style="color:#66d9ef">static</span> <span style="color:#66d9ef">void</span> <span style="color:#a6e22e">main</span>(String<span style="color:#f92672">[]</span> args) {
+</span></span><span style="display:flex;"><span>        <span style="color:#75715e">// ...</span>
+</span></span><span style="display:flex;"><span>    }
+</span></span><span style="display:flex;"><span>}</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Okay that&rsquo;s done. What do we do next? Let&rsquo;s look at <code>String[] args</code> argument to our <code>main</code> method. It represents an array of command line arguments which we need to sum. So know we made our task a little bit easier. Now we can just say that we need to find sum of elements of array <code>args</code>.</p>
+<p>How are we going to do it though? First let&rsquo;s understand what we can do with this array. Let&rsquo;s modify our class a little bit.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-java" data-lang="java"><span style="display:flex;"><span><span style="color:#75715e">// Sum.java</span>
+</span></span><span style="display:flex;"><span>
+</span></span><span style="display:flex;"><span><span style="color:#66d9ef">public</span> <span style="color:#66d9ef">class</span> <span style="color:#a6e22e">Sum</span> {
+</span></span><span style="display:flex;"><span>    <span style="color:#66d9ef">public</span> <span style="color:#66d9ef">static</span> <span style="color:#66d9ef">void</span> <span style="color:#a6e22e">main</span>(String<span style="color:#f92672">[]</span> args) {
+</span></span><span style="display:flex;"><span>        System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(args.<span style="color:#a6e22e">length</span>);
+</span></span><span style="display:flex;"><span>    }
+</span></span><span style="display:flex;"><span>}</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>We&rsquo;ve added <code>System.out.println(args.length)</code> which takes the field <code>length</code> from our <code>args</code> object and prints it to the console.</p>
+<p>Let&rsquo;s try it. First compile our class using</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ javac Sum.java</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>And then we can do some manual testing.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span> <span style="color:#ae81ff">3</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">3</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>We got <code>3</code> as an output as expected. We gave our program 3 command line arguments: <code>1</code>, <code>2</code> and <code>3</code>.</p>
+<p>Here are all of the examples</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span> -3
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">3</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#e6db74">&#34;1 2 3&#34;</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">1</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hx:overflow-x-auto hx:mt-6 hx:flex hx:flex-col hx:rounded-lg hx:border hx:py-4 hx:px-4 hx:border-gray-200 hx:contrast-more:border-current hx:contrast-more:dark:border-current hx:border-blue-200 hx:bg-blue-100 hx:text-blue-900 hx:dark:border-blue-200/30 hx:dark:bg-blue-900/30 hx:dark:text-blue-200">
+  <p class="hx:flex hx:items-center hx:font-medium"><svg height=16px class="hx:inline-block hx:align-middle hx:mr-2" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M13 16h-1v-4h-1m1-4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z"/></svg>Note</p>
+
+  <div class="hx:w-full hx:min-w-0 hx:leading-7">
+    <div class="hx:mt-6 hx:leading-7 hx:first:mt-0"><p>Notice, that we got 1 instead of 3. That&rsquo;s because we put our arguments in <code>&quot;&quot;</code> so this becomes a single string argument.</p></div>
+  </div>
+</div>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#e6db74">&#34;1 2&#34;</span> <span style="color:#e6db74">&#34; 3&#34;</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">2</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#e6db74">&#34; &#34;</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">1</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hx:overflow-x-auto hx:mt-6 hx:flex hx:flex-col hx:rounded-lg hx:border hx:py-4 hx:px-4 hx:border-gray-200 hx:contrast-more:border-current hx:contrast-more:dark:border-current hx:border-blue-200 hx:bg-blue-100 hx:text-blue-900 hx:dark:border-blue-200/30 hx:dark:bg-blue-900/30 hx:dark:text-blue-200">
+  <p class="hx:flex hx:items-center hx:font-medium"><svg height=16px class="hx:inline-block hx:align-middle hx:mr-2" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M13 16h-1v-4h-1m1-4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z"/></svg>Note</p>
+
+  <div class="hx:w-full hx:min-w-0 hx:leading-7">
+    <div class="hx:mt-6 hx:leading-7 hx:first:mt-0"><p>Here program gives us 1 instead of 0, because despite not having any numbers in the arguments a single whitespace is still an argument.</p></div>
+  </div>
+</div>
+<p>Now let&rsquo;s try not obly to count our arguments but to list them as well. Let&rsquo;s modify our program a little bit more.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-java" data-lang="java"><span style="display:flex;"><span><span style="color:#75715e">// Sum.java</span>
+</span></span><span style="display:flex;"><span>
+</span></span><span style="display:flex;"><span><span style="color:#66d9ef">public</span> <span style="color:#66d9ef">class</span> <span style="color:#a6e22e">Sum</span> {
+</span></span><span style="display:flex;"><span>    <span style="color:#66d9ef">public</span> <span style="color:#66d9ef">static</span> <span style="color:#66d9ef">void</span> <span style="color:#a6e22e">main</span>(String<span style="color:#f92672">[]</span> args) {
+</span></span><span style="display:flex;"><span>        System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(<span style="color:#e6db74">&#34;number of arguments: &#34;</span> <span style="color:#f92672">+</span> args.<span style="color:#a6e22e">length</span>);
+</span></span><span style="display:flex;"><span>        
+</span></span><span style="display:flex;"><span>        <span style="color:#66d9ef">for</span> (String argument : args) {
+</span></span><span style="display:flex;"><span>            System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(argument);
+</span></span><span style="display:flex;"><span>        }
+</span></span><span style="display:flex;"><span>    }
+</span></span><span style="display:flex;"><span>}</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Here I used <code>for</code> loop to do printing <em><strong>for</strong></em> every <code>String</code> element in <code>args</code>.</p>
+<p>Let&rsquo;s try this with our examples. And don&rsquo;t forget to recompile using <code>javac Sum.java</code>.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span> <span style="color:#ae81ff">3</span>
+</span></span><span style="display:flex;"><span>number of arguments: <span style="color:#ae81ff">3</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">1</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">2</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">3</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span> -3
+</span></span><span style="display:flex;"><span>number of arguments: <span style="color:#ae81ff">3</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">1</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">2</span>
+</span></span><span style="display:flex;"><span>-3</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#e6db74">&#34;1 2 3&#34;</span>
+</span></span><span style="display:flex;"><span>number of arguments: <span style="color:#ae81ff">1</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span> <span style="color:#ae81ff">3</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hx:overflow-x-auto hx:mt-6 hx:flex hx:flex-col hx:rounded-lg hx:border hx:py-4 hx:px-4 hx:border-gray-200 hx:contrast-more:border-current hx:contrast-more:dark:border-current hx:border-blue-200 hx:bg-blue-100 hx:text-blue-900 hx:dark:border-blue-200/30 hx:dark:bg-blue-900/30 hx:dark:text-blue-200">
+  <p class="hx:flex hx:items-center hx:font-medium"><svg height=16px class="hx:inline-block hx:align-middle hx:mr-2" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M13 16h-1v-4h-1m1-4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z"/></svg>Note</p>
+
+  <div class="hx:w-full hx:min-w-0 hx:leading-7">
+    <div class="hx:mt-6 hx:leading-7 hx:first:mt-0"><p>Again, notice only <em><strong>one</strong></em> string argument.</p></div>
+  </div>
+</div>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#e6db74">&#34;1 2&#34;</span> <span style="color:#e6db74">&#34; 3&#34;</span>
+</span></span><span style="display:flex;"><span>number of arguments: <span style="color:#ae81ff">2</span>
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">1</span> <span style="color:#ae81ff">2</span>
+</span></span><span style="display:flex;"><span> <span style="color:#ae81ff">3</span></span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ java Sum <span style="color:#e6db74">&#34; &#34;</span>
+</span></span><span style="display:flex;"><span>number of arguments: <span style="color:#ae81ff">1</span>
+</span></span><span style="display:flex;"><span> </span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Okay, now that we know how to <em><strong>iterate</strong></em> (or do something for every element), we can calculate the <em>sum</em> of all the numbers in the <code>args</code> array. To do that we need to create a new variable <code>sum</code> of <em>integer</em> type and assign it the <strong>value</strong> of <code>0</code>. Then for every number in <code>args</code> we will add it to <code>sum</code>, and so by the end of array we will have the sum of all numbers stored in variable <code>sum</code>. This is what the code will look like</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-java" data-lang="java"><span style="display:flex;"><span><span style="color:#75715e">// Sum.java</span>
+</span></span><span style="display:flex;"><span>
+</span></span><span style="display:flex;"><span><span style="color:#66d9ef">public</span> <span style="color:#66d9ef">class</span> <span style="color:#a6e22e">Sum</span> {
+</span></span><span style="display:flex;"><span>    <span style="color:#66d9ef">public</span> <span style="color:#66d9ef">static</span> <span style="color:#66d9ef">void</span> <span style="color:#a6e22e">main</span>(String<span style="color:#f92672">[]</span> args) {
+</span></span><span style="display:flex;"><span>        System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(<span style="color:#e6db74">&#34;number of arguments: &#34;</span> <span style="color:#f92672">+</span> args.<span style="color:#a6e22e">length</span>);
+</span></span><span style="display:flex;"><span>        
+</span></span><span style="display:flex;"><span>        <span style="color:#66d9ef">int</span> sum <span style="color:#f92672">=</span> 0;
+</span></span><span style="display:flex;"><span>        <span style="color:#66d9ef">for</span> (String argument : args) {
+</span></span><span style="display:flex;"><span>            sum <span style="color:#f92672">=</span> sum <span style="color:#f92672">+</span> argument;
+</span></span><span style="display:flex;"><span>            System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(argument);
+</span></span><span style="display:flex;"><span>            System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(sum);
+</span></span><span style="display:flex;"><span>        }
+</span></span><span style="display:flex;"><span>        
+</span></span><span style="display:flex;"><span>        System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(sum);
+</span></span><span style="display:flex;"><span>    }
+</span></span><span style="display:flex;"><span>}</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>Seems ok. But let&rsquo;s test it.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-sh" data-lang="sh"><span style="display:flex;"><span>$ javac Sum.java
+</span></span><span style="display:flex;"><span>Sum.java:9: error: incompatible types: String cannot be converted to int
+</span></span><span style="display:flex;"><span>            sum <span style="color:#f92672">=</span> sum + argument;
+</span></span><span style="display:flex;"><span>                      ^
+</span></span><span style="display:flex;"><span><span style="color:#ae81ff">1</span> error</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>We got a compilation error that says <code>String cannot be converted to int</code>. It means that when we try to add 2 variables <code>sum</code> and <code>argument</code> their types don&rsquo;t match. The type of <code>sum</code> is integer and string for <code>argument</code>. It seems pretty logical because what do we expect when adding for example <code>1</code> and <code>apple</code>?..</p>
+<div class="hx:overflow-x-auto hx:mt-6 hx:flex hx:flex-col hx:rounded-lg hx:border hx:py-4 hx:px-4 hx:border-gray-200 hx:contrast-more:border-current hx:contrast-more:dark:border-current hx:border-purple-200 hx:bg-purple-100 hx:text-purple-900 hx:dark:border-purple-200/30 hx:dark:bg-purple-900/30 hx:dark:text-purple-200">
+  <p class="hx:flex hx:items-center hx:font-medium"><svg height=16px class="hx:inline-block hx:align-middle hx:mr-2" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M13 16h-1v-4h-1m1-4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z"/></svg>Important</p>
+
+  <div class="hx:w-full hx:min-w-0 hx:leading-7">
+    <div class="hx:mt-6 hx:leading-7 hx:first:mt-0"><p>So we need to <em>cast</em> <code>argument</code> to integer data type so that we can add it to <code>sum</code>.</p></div>
+  </div>
+</div>
+<p>We can do so using <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html#parseInt-java.lang.String-"target="_blank" rel="noopener"><code>Integer.parseInt()</code></a> method.</p>
+<p>It takes a <code>String s</code> and returns an <code>int</code>, which a string <code>s</code> represents. For example this code will work as expected</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-java" data-lang="java"><span style="display:flex;"><span><span style="color:#75715e">// ParseIntExample.java</span>
+</span></span><span style="display:flex;"><span>
+</span></span><span style="display:flex;"><span><span style="color:#66d9ef">public</span> <span style="color:#66d9ef">class</span> <span style="color:#a6e22e">ParseIntExample</span> {
+</span></span><span style="display:flex;"><span>
+</span></span><span style="display:flex;"><span>    <span style="color:#66d9ef">public</span> <span style="color:#66d9ef">static</span> <span style="color:#66d9ef">void</span> <span style="color:#a6e22e">main</span>(String<span style="color:#f92672">[]</span> args) {
+</span></span><span style="display:flex;"><span>        String s <span style="color:#f92672">=</span> <span style="color:#e6db74">&#34;123&#34;</span>;
+</span></span><span style="display:flex;"><span>        <span style="color:#66d9ef">int</span> sum <span style="color:#f92672">=</span> 321;
+</span></span><span style="display:flex;"><span>        <span style="color:#75715e">//! sum = sum + s;</span>
+</span></span><span style="display:flex;"><span>        sum <span style="color:#f92672">=</span> sum <span style="color:#f92672">+</span> Integer.<span style="color:#a6e22e">parseInt</span>(s);
+</span></span><span style="display:flex;"><span>        System.<span style="color:#a6e22e">out</span>.<span style="color:#a6e22e">println</span>(sum);
+</span></span><span style="display:flex;"><span>    }
+</span></span><span style="display:flex;"><span>}</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>The commented out line (<code>//!</code>) would have given us an exception.</p>
+
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+          <li class="open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/"
+    
+  >Courses
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a>
+              
+            </li><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+  
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:max-md:hidden">
+        
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a></li>
+          <li class="open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div></li>
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a></li>
+        
+      </ul>
+    </div>
+  
+  
+    <div class="  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
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+      >
+        Dark
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+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+  </ul>
+</div></div></div></aside>
+    
+<nav class="hextra-toc hx:order-last hx:hidden hx:w-64 hx:shrink-0 hx:xl:block hx:print:hidden hx:px-4" aria-label="table of contents">
+    <div class="hextra-scrollbar hx:sticky hx:top-16 hx:overflow-y-auto hx:pr-4 hx:pt-6 hx:text-sm [hyphens:auto] hx:max-h-[calc(100vh-var(--navbar-height)-env(safe-area-inset-bottom))] hx:ltr:-mr-4 hx:rtl:-ml-4">
+      <div class=" hx:sticky hx:bottom-0 hx:flex hx:flex-col hx:items-start hx:gap-2 hx:pb-8 hx:border-gray-200 hx:dark:border-neutral-800 hx:contrast-more:border-t hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:border-neutral-400">
+        <button aria-hidden="true" id="backToTop" onClick="scrollUp();" class="hx:cursor-pointer hx:transition-all hx:duration-75 hx:opacity-0 hx:text-xs hx:font-medium hx:text-gray-500 hx:hover:text-gray-900 hx:dark:text-gray-400 hx:dark:hover:text-gray-100 hx:contrast-more:text-gray-800 hx:contrast-more:dark:text-gray-50">
+          <span>Scroll to top</span>
+          <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="hx:inline hx:ltr:ml-1 hx:rtl:mr-1 hx:h-3.5 hx:w-3.5 hx:rounded-full hx:border hx:border-gray-500 hx:hover:border-gray-900 hx:dark:border-gray-400 hx:dark:hover:border-gray-100 hx:contrast-more:border-gray-800 hx:contrast-more:dark:border-gray-50">
+            <path stroke-linecap="round" stroke-linejoin="round" d="M4.5 15.75l7.5-7.5 7.5 7.5" />
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+        </button>
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+  </nav>
+
+
+    <article class="hx:w-full hx:break-words hx:flex hx:min-h-[calc(100vh-var(--navbar-height))] hx:min-w-0 hx:justify-center hx:pb-8 hx:pr-[calc(env(safe-area-inset-right)-1.5rem)]">
+      <main class="hx:w-full hx:min-w-0 hx:max-w-6xl hx:px-6 hx:pt-4 hx:md:px-12">
+        
+        <div class="content">
+          <h1>Introduction to Programming in Java</h1>
+          
+        </div>
+        <div class="hx:mt-16"></div>
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+        
+      </main>
+    </article>
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+    >
+      <div class="hx:flex hx:w-full hx:flex-col hx:items-center hx:sm:items-start"><div class="hx:font-semibold"><a class="hx:flex hx:text-sm hx:items-center hx:gap-1 hx:text-current" target="_blank" rel="noopener noreferrer" title="Hextra GitHub Homepage" href="https://github.com/imfing/hextra">
+    <span>Powered by Hextra<svg height=1em class="hx:inline-block hx:ltr:ml-1 hx:rtl:mr-1 hx:align-[-2.5px]" viewBox="0 0 180 180" xmlns="http://www.w3.org/2000/svg" fill="currentColor"><path fill-rule="evenodd" clip-rule="evenodd" d="m 105.50024,22.224647 c -9.59169,-5.537563 -21.40871,-5.537563 -31.000093,0 L 39.054693,42.689119 C 29.463353,48.226675 23.55484,58.460531 23.55484,69.535642 v 40.928918 c 0,11.07542 5.908513,21.3092 15.499853,26.84652 l 35.445453,20.46446 c 9.591313,5.53732 21.408404,5.53732 31.000094,0 l 35.44507,-20.46446 c 9.59131,-5.53732 15.49985,-15.7711 15.49985,-26.84652 V 69.535642 c 0,-11.075111 -5.90854,-21.308967 -15.49985,-26.846523 z M 34.112797,85.737639 c -1.384445,2.397827 -1.384445,5.352099 0,7.749927 l 24.781554,42.922974 c 1.38437,2.39783 3.942853,3.87496 6.711592,3.87496 h 49.563107 c 2.76905,0 5.3273,-1.47713 6.71144,-3.87496 l 24.78194,-42.922974 c 1.38414,-2.397828 1.38414,-5.3521 0,-7.749927 L 121.88049,42.814746 c -1.38414,-2.397828 -3.94239,-3.874964 -6.71144,-3.874964 H 65.605944 c -2.768739,0 -5.327223,1.477059 -6.711592,3.874964 z" style="stroke-width:0.774993" /></svg></span>
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+        <script defer src="/en.search.js" integrity=""></script>
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+</html>

public/courses/prog-intro/index.xml

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+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>CodeJava – Introduction to Programming in Java</title>
+    <link>http://localhost:1313/courses/prog-intro/</link>
+    <description>Recent content in Introduction to Programming in Java on CodeJava</description>
+    <generator>Hugo -- gohugo.io</generator>
+    <language>en</language>
+    
+	  <atom:link href="http://localhost:1313/courses/prog-intro/index.xml" rel="self" type="application/rss+xml" />
+    
+    
+      
+        
+      
+    
+    
+    <item>
+      <title>Homeworks</title>
+      <link>http://localhost:1313/courses/prog-intro/homeworks/</link>
+      <pubDate>Mon, 01 Jan 0001 00:00:00 +0000</pubDate>
+      
+      <guid>http://localhost:1313/courses/prog-intro/homeworks/</guid>
+      <description>
+        
+        
+        
+      </description>
+    </item>
+    
+    <item>
+      <title>Lectures</title>
+      <link>http://localhost:1313/courses/prog-intro/lectures/</link>
+      <pubDate>Mon, 01 Jan 0001 00:00:00 +0000</pubDate>
+      
+      <guid>http://localhost:1313/courses/prog-intro/lectures/</guid>
+      <description>
+        
+        
+        
+      </description>
+    </item>
+    
+  </channel>
+</rss>

public/courses/prog-intro/lectures/index.html

@@ -0,0 +1,385 @@
+<!DOCTYPE html>
+<html lang="en" dir="ltr"><head><script src="/livereload.js?mindelay=10&amp;v=2&amp;port=1313&amp;path=livereload" data-no-instant defer></script>
+  <meta charset="utf-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="robots" content="noindex, nofollow" />
+  <link rel="icon shortcut" href="/favicon.ico" sizes="32x32" />
+<link rel="icon" href="/favicon.svg" type="image/svg+xml" id="favicon-svg" />
+<link rel="icon" href="/favicon-16x16.png" type="image/png" sizes="16x16" />
+<link rel="icon" href="/favicon-32x32.png" type="image/png" sizes="32x32" />
+<link rel="apple-touch-icon" href="/apple-touch-icon.png" sizes="180x180" />
+<link fetchpriority="low" href="/site.webmanifest" rel="manifest" />
+<title>Lectures – CodeJava</title>
+  <meta name="description" content="" /><link rel="canonical" href="http://localhost:1313/courses/prog-intro/lectures/" itemprop="url" />
+
+<meta property="og:title" content="Lectures">
+<meta
+  property="og:description"
+  content="
+    
+      Learn Java programming
+    
+  ">
+<meta
+  property="og:type"
+  content="
+    website
+  ">
+<meta property="og:url" content="http://localhost:1313/courses/prog-intro/lectures/">
+
+
+  <meta itemprop="name" content="Lectures">
+  <meta itemprop="description" content="Learn Java programming">
+  <meta name="twitter:card" content="summary">
+  <meta name="twitter:title" content="Lectures">
+  <meta name="twitter:description" content="Learn Java programming">
+<link href="/css/compiled/main.css" rel="stylesheet" />
+    <link href="/css/variables.css" rel="stylesheet" />
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+
+  
+
+
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+    
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+      document.documentElement.classList.remove("light", "dark");
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+      if (theme !== "light" && theme !== "dark") {
+       theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
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+      document.documentElement.classList.add(theme);
+      document.documentElement.style.colorScheme = theme;
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+    setTheme("color-theme" in localStorage ? localStorage.getItem("color-theme") : 'system')
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+
+  
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+  </head>
+<body><div class="hextra-nav-container hx:sticky hx:top-0 hx:z-20 hx:w-full hx:bg-transparent hx:print:hidden">
+  <div
+    class="hextra-nav-container-blur hx:pointer-events-none hx:absolute hx:z-[-1] hx:h-full hx:w-full hx:bg-white hx:dark:bg-dark hx:shadow-[0_2px_4px_rgba(0,0,0,.02),0_1px_0_rgba(0,0,0,.06)] hx:contrast-more:shadow-[0_0_0_1px_#000] hx:dark:shadow-[0_-1px_0_rgba(255,255,255,.1)_inset] hx:contrast-more:dark:shadow-[0_0_0_1px_#fff]"
+  ></div>
+
+  <nav class="hextra-max-navbar-width hx:mx-auto hx:flex hx:items-center hx:justify-end hx:gap-2 hx:h-16 hx:px-6">
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+</a>
+<a
+  title=""
+  href="/courses"
+  
+  class="hx:text-sm hx:contrast-more:text-gray-700 hx:contrast-more:dark:text-gray-100 hx:relative hx:-ml-2 hx:hidden hx:whitespace-nowrap hx:p-2 hx:md:inline-flex hx:items-center hx:gap-1 hx:font-medium"
+><span class="hx:text-center">Courses</span>
+</a><div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+<button type="button" aria-label="Menu" class="hextra-hamburger-menu hx:cursor-pointer hx:-mr-2 hx:rounded-sm hx:p-2 hx:active:bg-gray-400/20 hx:md:hidden"><svg height=24 fill="none" viewBox="0 0 24 24" stroke="currentColor"><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 8H20"></path></g><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16H20"></path></g></svg></button>
+  </nav>
+</div>
+
+  <div class='hx:mx-auto hx:flex hextra-max-page-width'>
+    <aside class="hextra-sidebar-container hx:flex hx:flex-col hx:print:hidden hx:md:top-16 hx:md:shrink-0 hx:md:w-64 hx:md:self-start hx:max-md:[transform:translate3d(0,-100%,0)] hx:md:sticky">
+  
+  <div class="hx:px-4 hx:pt-4 hx:md:hidden">
+    <div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+
+  </div>
+  <div class="hextra-scrollbar hx:overflow-y-auto hx:overflow-x-hidden hx:p-4 hx:grow hx:md:h-[calc(100vh-var(--navbar-height)-var(--menu-height))]">
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+      
+      
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+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/"
+    
+  >Courses
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a>
+              
+            </li><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+  
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:max-md:hidden">
+        
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a></li>
+          <li class="open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div></li>
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a></li>
+        
+      </ul>
+    </div>
+  
+  
+    <div class="  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
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+        &lt;h1&gt;Why do we choose Java?&lt;/h1&gt;&lt;p&gt;According to &lt;strong&gt;TIOBE Programming Community Index&lt;/strong&gt; Java is one of the most demanded languages in the programming field.&lt;/p&gt;
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+    &lt;img src=&#34;../assets/tiobe.png&#34; alt=&#34;TIOBE Programming Community Index&#34;  loading=&#34;lazy&#34; /&gt;
+&lt;em&gt;Img. 1 - TIOBE Programming Community Index&lt;/em&gt;&lt;/p&gt;
+&lt;p&gt;Also, Java has a lot of advantages for beginners such as:&lt;/p&gt;
+&lt;ul&gt;
+&lt;li&gt;It&amp;rsquo;s fairly easy&lt;/li&gt;
+&lt;li&gt;It has a broad spectre of usage
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+&lt;li&gt;Server&lt;/li&gt;
+&lt;li&gt;Desktop&lt;/li&gt;
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+&lt;li&gt;Smart-cards&lt;/li&gt;
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+&lt;h1&gt;What does Java consist of?&lt;/h1&gt;&lt;p&gt;Java consists of multiple main components. The first one being the &lt;strong&gt;Java compiler&lt;/strong&gt;. The process of converting &lt;em&gt;human-readable&lt;/em&gt; text to &lt;em&gt;machine code&lt;/em&gt; is called &lt;strong&gt;compilation&lt;/strong&gt;.&lt;/p&gt;
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+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/"
+    
+  >Courses
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a>
+              
+            </li><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col open"><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hextra-sidebar-active-item hx:bg-primary-100 hx:font-semibold hx:text-primary-800 hx:contrast-more:border hx:contrast-more:border-primary-500 hx:dark:bg-primary-400/10 hx:dark:text-primary-600 hx:contrast-more:dark:border-primary-500"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+  
+    <ul class='hx:flex hx:flex-col hx:gap-1 hx:relative hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:dark:before:bg-neutral-800 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:pr-3 hx:rtl:before:right-0 hx:ltr:ml-3 hx:rtl:mr-3'></ul>
+  
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <div class="hx:max-xl:hidden hx:h-0 hx:w-64 hx:shrink-0"></div></div>
+  
+  
+    <div class="hx:md:hidden  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
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+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
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+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
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+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
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+</div></div></div></aside>
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+    <article class="hx:w-full hx:break-words hx:flex hx:min-h-[calc(100vh-var(--navbar-height))] hx:min-w-0 hx:justify-center hx:pb-8 hx:pr-[calc(env(safe-area-inset-right)-1.5rem)]">
+      <main class="hx:w-full hx:min-w-0 hx:max-w-6xl hx:px-6 hx:pt-4 hx:md:px-12">
+        
+        <br class="hx:mt-1.5 hx:text-sm" />
+        <h1 class="hx:text-center hx:mt-2 hx:text-4xl hx:font-bold hx:tracking-tight hx:text-slate-900 hx:dark:text-slate-100">Lecture 1. Introduction</h1>
+        <div class="hx:mb-16"></div>
+        <div class="content">
+          <h1>Why do we choose Java?</h1><p>According to <strong>TIOBE Programming Community Index</strong> Java is one of the most demanded languages in the programming field.</p>
+<p>
+    <img src="../assets/tiobe.png" alt="TIOBE Programming Community Index"  loading="lazy" />
+<em>Img. 1 - TIOBE Programming Community Index</em></p>
+<p>Also, Java has a lot of advantages for beginners such as:</p>
+<ul>
+<li>It&rsquo;s fairly easy</li>
+<li>It has a broad spectre of usage
+<ul>
+<li>Server</li>
+<li>Desktop</li>
+<li>Mobile devices</li>
+<li>Smart-cards</li>
+</ul>
+</li>
+</ul>
+<h1>What does Java consist of?</h1><p>Java consists of multiple main components. The first one being the <strong>Java compiler</strong>. The process of converting <em>human-readable</em> text to <em>machine code</em> is called <strong>compilation</strong>.</p>
+<p>
+    <img src="../assets/compilation-process-simplified.svg" alt="Compilation Process Simplified"  loading="lazy" />
+<em>Img.2 - Simplified Compilation Process</em></p>
+<p>The behaviour of the Java compiler is described by the <a href="https://docs.oracle.com/javase/specs/"target="_blank" rel="noopener">Java Language Specification</a> or JLS.</p>
+<p>Let&rsquo;s talk about compilers a little bit. For example if we will take <em>C++</em>. If we take C++ compiler for <em>x86-64</em> platform and <em>Windows</em> operating system, and launch the compiler on source code it will turn it directly into assembly code.</p>
+<p>
+    <img src="../assets/cpp-x86-64-compilation.svg" alt="C&#43;&#43; code compilation under x86-64"  loading="lazy" />
+<em>Img. X &ndash; C++ code compilation process under x86-64 architecture.</em></p>
+<p>But what if I want to run my program on <em>Linux</em> instead of Windows. I will need to take a different compiler under different operating system and recompile my code using a new compiler. It&rsquo;s not very convenient.</p>
+<p>Java tries to protect us from that. By converting the <em>Java source code</em> into <em>Java byte code</em>. And then the <em>byte code</em> will be ran on the <em>Java virtual machine</em> which will run our program on the native processor.</p>
+<p>
+    <img src="../assets/java-code-compilation.svg" alt="Java code compilation"  loading="lazy" />
+<em>Img. X &ndash; Java code compilation</em></p>
+<p>This approach allows to change only <strong>JVM</strong> according to our platform (<em>x86_64, ARM, &hellip;</em>) and operating system (<em>Windows, MacOS, GNU-Linux, &hellip;</em>) while <em>byte code</em> stays the same. We can only write our code once, than compile it and run under everywhere.</p>
+<p>As the motto says:</p>
+<blockquote>
+  <p>Write once &ndash; <del>debug</del> run everywhere.</p>
+
+</blockquote>
+<p>The third component of Java is the standart library which is included in the JVM.</p>
+<p>There are multiple redactions of Java-platforms:</p>
+<ul>
+<li>Standart edition
+<ul>
+<li><em>For regular aplications</em></li>
+</ul>
+</li>
+<li>Enterprise edition
+<ul>
+<li><em>For server aplications</em></li>
+</ul>
+</li>
+<li>Micro-edition
+<ul>
+<li><em>For mobile aplications</em></li>
+<li><em>Isn&rsquo;t in use nowadays 🪦</em></li>
+</ul>
+</li>
+<li>Java Card
+<ul>
+<li><em>Sim- and smart-cards</em></li>
+</ul>
+</li>
+</ul>
+<p>There also were multiple versions of Java throughout its history.</p>
+<ul>
+<li>JDK 1.0 (Jan 1996)</li>
+<li>J2SE 1.2 (Dec 1998)
+<ul>
+<li><em>Collections Framework</em></li>
+</ul>
+</li>
+<li>J2SE 5.0 (Sep 2004)
+<ul>
+<li><em>Generics</em></li>
+</ul>
+</li>
+<li>Java SE 8 (Mar 2014)
+<ul>
+<li><em>Streams and Lambdas</em></li>
+</ul>
+</li>
+<li>Java SE 9 (Sep 2017)
+<ul>
+<li><em>Modules</em></li>
+</ul>
+</li>
+<li>Java SE 10 (Mar 2018)
+<ul>
+<li><code>var</code></li>
+</ul>
+</li>
+<li>Java 11 (Sep 2018)
+<ul>
+<li><code>jshell</code></li>
+</ul>
+</li>
+<li>Java 17 [LTS-old] (Sep 2021)
+<ul>
+<li><em>Previous stable version</em></li>
+<li><em>Many little changes</em></li>
+</ul>
+</li>
+<li>Java 21 [LTS] (Sep 2023)
+<ul>
+<li><em>Current stable version</em></li>
+</ul>
+</li>
+<li>Java 25 (Sep 2025)
+<ul>
+<li><em>Next version</em></li>
+</ul>
+</li>
+</ul>
+<p>Java comes in two parts: <strong>JDK - Java Development Kit</strong> and <strong>JVM - Java Virtual Machine</strong>.</p>
+<p>There is also a <strong>JRE - Java Runtime Environment</strong>. For example if we want to run our code somewhere on the server we don&rsquo;t need to compile it there because we have our byte code and we just need JRE to run it.</p>
+<p>Some of the most popular JVMs right now are:</p>
+<ul>
+<li>OpenJDK</li>
+<li>Eclipse</li>
+<li>Azul Systems</li>
+<li>Excelsior JET</li>
+</ul>
+<p>The disadvantage of such system is in the connection between JVM and a native processing unit. In case of C++ compiler that we reviewed earlier the source code is compiled directly into machine-code but in case with Java it is compiled into byte-code. And so the problem is to develop such a JVM that would quickly turn our byte-code into machine-code. Anyway it takes extra time. That&rsquo;s why it mostly will be slower than direct compilation into machine-code. So ultimately while we have the advantage of compiling out code only once, we have the disadvantage of turning byte-code into machine-code slower.</p>
+<p>None the less, there is a way to speed up this process which is called JIT - Just In Time compilation. How does it work? While our program is running some of the instructions or functions turns directly into processor commands.</p>
+<h1>What is garbage collection?</h1><p>For example we have <code>int</code> which is represented with 4 bytes of data which is directly stored in memory.</p>
+<p>
+    <img src="../assets/int-in-memory.svg" alt="int in memory"  loading="lazy" />
+<em>Img. X &ndash; <code>int</code> in memory</em></p>
+<p>But what if we have a <code>String</code>. How many memory cells does this string take? We don&rsquo;t know. We will say that our <code>String</code> that has length of 5 symbols is stored at <code>0x12347865</code>. We defined an address where this string is located in memory. And somewhere in the memory of our programm will be a large buffer where the 5 cells will be stored.</p>
+<p>
+    <img src="../assets/string-in-memory.svg" alt="String in memory"  loading="lazy" />
+<em>Img. X &ndash; <code>String</code> in memory</em></p>
+<p>But what do we do with that buffer? We won&rsquo;t need it forever and so sometimes we need to clear that buffer. In case with C/C++ whoever created the memory for that string is in charge of clearing it. There are also languages with garbage collection such as Java and Python. The purpose of the <strong>Garbage Collector</strong> is to automatically find variables that we no longer need and clear their memory.</p>
+<p>Suppose we have some code like this.</p>
+<div class="hextra-code-block hx:relative hx:mt-6 hx:first:mt-0 hx:group/code">
+
+<div><div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"><code class="language-java" data-lang="java"><span style="display:flex;"><span><span style="color:#66d9ef">if</span> (someCondition) { 
+</span></span><span style="display:flex;"><span>    x <span style="color:#f92672">=</span> <span style="color:#f92672">[</span>1, 3, 7<span style="color:#f92672">]</span> <span style="color:#75715e">// first link </span>
+</span></span><span style="display:flex;"><span>    <span style="color:#75715e">// some code here </span>
+</span></span><span style="display:flex;"><span>    y <span style="color:#f92672">=</span> x <span style="color:#75715e">// second link </span>
+</span></span><span style="display:flex;"><span>    <span style="color:#75715e">// some code here </span>
+</span></span><span style="display:flex;"><span>} <span style="color:#f92672">//</span> no links</span></span></code></pre></div></div><div class="hextra-code-copy-btn-container hx:opacity-0 hx:transition hx:group-hover/code:opacity-100 hx:flex hx:gap-1 hx:absolute hx:m-[11px] hx:right-0 hx:top-0">
+  <button
+    class="hextra-code-copy-btn hx:group/copybtn hx:cursor-pointer hx:transition-all hx:active:opacity-50 hx:bg-primary-700/5 hx:border hx:border-black/5 hx:text-gray-600 hx:hover:text-gray-900 hx:rounded-md hx:p-1.5 hx:dark:bg-primary-300/10 hx:dark:border-white/10 hx:dark:text-gray-400 hx:dark:hover:text-gray-50"
+    title="Copy code"
+  >
+    <div class="hextra-copy-icon hx:group-[.copied]/copybtn:hidden hx:pointer-events-none hx:h-4 hx:w-4"></div>
+<div class="hextra-success-icon hx:hidden hx:group-[.copied]/copybtn:block hx:pointer-events-none hx:h-4 hx:w-4"></div>
+  </button>
+</div>
+</div>
+<p>After the <code>if</code>-statement we no longer need <code>x</code> or <code>y</code>. Every variable in this case <code>x</code> and <code>y</code> is the link to our array (<code>[1, 3, 7]</code>). After we left the <code>if</code>-statement the amount of links to the array is zero, so we can safely delete the array. This approach is implemented in Python. The problem is that if we have to objects linked to one another and there are no external links, they will not be deleted by garbage collector since there link counter is 1.</p>
+<p>
+    <img src="../assets/edge-case-for-link-counting.svg" alt="Edge case for link couting"  loading="lazy" />
+<em>Img. X &ndash; Edge case for link counting</em></p>
+<p>The advanced way of implementing the garbage collection is <em>traversing the graph of links</em> which is implemented in Java, C# and Go.</p>
+<h1>What other advantages does Java have?</h1><ul>
+<li>It&rsquo;s easy (in terms of syntax)</li>
+<li>It&rsquo;s secure and stable</li>
+<li>It supports Unicode</li>
+<li>It supports multithreading</li>
+<li>It has backwards compatibility</li>
+</ul>
+<h1>How should Java code look like?</h1><p>You can go and learn about it <a href="https://google.github.io/styleguide/javaguide.html"target="_blank" rel="noopener">here</a>.</p>
+
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+  </button>
+  <ul
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+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
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+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
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public/courses/spring-boot/index.xml

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+  <channel>
+    <title>CodeJava – </title>
+    <link>http://localhost:1313/courses/spring-boot/</link>
+    <description>Recent content on CodeJava</description>
+    <generator>Hugo -- gohugo.io</generator>
+    <language>en</language>
+    
+	  <atom:link href="http://localhost:1313/courses/spring-boot/index.xml" rel="self" type="application/rss+xml" />
+    
+    
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+    
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+</rss>

public/css/variables.css

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+/* Hugo template to derive CSS variables from site and page parameters */
+
+/* Do not remove the following comment. It is used by Hugo to render CSS variables.*/
+
+:root {
+  --hextra-max-page-width: 80rem;
+  --hextra-max-navbar-width: 80rem;
+  --hextra-max-footer-width: 80rem;
+}
+
+.hextra-max-page-width {
+  max-width: var(--hextra-max-page-width);
+}
+
+.hextra-max-navbar-width {
+  max-width: var(--hextra-max-navbar-width);
+}
+
+.hextra-max-footer-width {
+  max-width: var(--hextra-max-footer-width);
+}

public/en.search.js

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+
+// Change shortcut key to cmd+k on Mac, iPad or iPhone.
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+  if (/iPad|iPhone|Macintosh/.test(navigator.userAgent)) {
+    // select the kbd element under the .hextra-search-wrapper class
+    const keys = document.querySelectorAll(".hextra-search-wrapper kbd");
+    keys.forEach(key => {
+      key.innerHTML = '<span class="hx:text-xs">⌘</span>K';
+    });
+  }
+});
+
+// Render the search data as JSON.
+// 
+// 
+// 
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+
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+
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+
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+
+  function handleInputChange(e) {
+    const opacity = e.target.value.length > 0 ? 0 : 100;
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+    const { inputElement } = getActiveSearchElement();
+    if (!inputElement) return;
+
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+      inputElement.focus();
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+  // Dismiss the search results when clicking outside the search box.
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+      setShortcutElementsOpacity(100);
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+  // Get the currently active result and its index.
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+
+    const index = parseInt(result.dataset.index, 10);
+    return { result, index };
+  }
+
+  // Set the active result by index.
+  function setActiveResult(index) {
+    const { resultsElement } = getActiveSearchElement();
+    if (!resultsElement) return;
+
+    const { result: activeResult } = getActiveResult();
+    activeResult && activeResult.classList.remove('hextra-search-active');
+    const result = resultsElement.querySelector(`[data-index="${index}"]`);
+    if (result) {
+      result.classList.add('hextra-search-active');
+      result.focus();
+    }
+  }
+
+  // Get the number of search results from the DOM.
+  function getResultsLength() {
+    const { resultsElement } = getActiveSearchElement();
+    if (!resultsElement) return 0;
+    return resultsElement.dataset.count;
+  }
+
+  // Finish the search by hiding the results and clearing the input.
+  function finishSearch() {
+    const { inputElement } = getActiveSearchElement();
+    if (!inputElement) return;
+    hideSearchResults();
+    inputElement.value = '';
+    inputElement.blur();
+  }
+
+  function hideSearchResults() {
+    const { resultsElement } = getActiveSearchElement();
+    if (!resultsElement) return;
+    resultsElement.classList.add('hx:hidden');
+  }
+
+  // Handle keyboard events.
+  function handleKeyDown(e) {
+    const { inputElement } = getActiveSearchElement();
+    if (!inputElement) return;
+
+    const resultsLength = getResultsLength();
+    const { result: activeResult, index: activeIndex } = getActiveResult();
+
+    switch (e.key) {
+      case 'ArrowUp':
+        e.preventDefault();
+        if (activeIndex > 0) setActiveResult(activeIndex - 1);
+        break;
+      case 'ArrowDown':
+        e.preventDefault();
+        if (activeIndex + 1 < resultsLength) setActiveResult(activeIndex + 1);
+        break;
+      case 'Enter':
+        e.preventDefault();
+        if (activeResult) {
+          activeResult.click();
+        }
+        finishSearch();
+      case 'Escape':
+        e.preventDefault();
+        hideSearchResults();
+        // Clear the input when pressing escape
+        inputElement.value = '';
+        inputElement.dispatchEvent(new Event('input'));
+        // Remove focus from the input
+        inputElement.blur();
+        break;
+    }
+  }
+
+  // Initializes the search.
+  function init(e) {
+    e.target.removeEventListener('focus', init);
+    if (!(window.pageIndex && window.sectionIndex)) {
+      preloadIndex();
+    }
+  }
+
+  /**
+   * Preloads the search index by fetching data and adding it to the FlexSearch index.
+   * @returns {Promise<void>} A promise that resolves when the index is preloaded.
+   */
+  async function preloadIndex() {
+    const tokenize = 'forward';
+
+    // https://github.com/TryGhost/Ghost/pull/21148
+    const regex = new RegExp(
+      `[\u{4E00}-\u{9FFF}\u{3040}-\u{309F}\u{30A0}-\u{30FF}\u{AC00}-\u{D7A3}\u{3400}-\u{4DBF}\u{20000}-\u{2A6DF}\u{2A700}-\u{2B73F}\u{2B740}-\u{2B81F}\u{2B820}-\u{2CEAF}\u{2CEB0}-\u{2EBEF}\u{30000}-\u{3134F}\u{31350}-\u{323AF}\u{2EBF0}-\u{2EE5F}\u{F900}-\u{FAFF}\u{2F800}-\u{2FA1F}]|[0-9A-Za-zа-я\u00C0-\u017F\u0400-\u04FF\u0600-\u06FF\u0980-\u09FF\u1E00-\u1EFF\u0590-\u05FF]+`,
+      'mug'
+    );
+    const encode = (str) => { return ('' + str).toLowerCase().match(regex) ?? []; }
+
+    window.pageIndex = new FlexSearch.Document({
+      tokenize,
+      encode,
+      cache: 100,
+      document: {
+        id: 'id',
+        store: ['title', 'crumb'],
+        index: "content"
+      }
+    });
+
+    window.sectionIndex = new FlexSearch.Document({
+      tokenize,
+      encode,
+      cache: 100,
+      document: {
+        id: 'id',
+        store: ['title', 'content', 'url', 'display', 'crumb'],
+        index: "content",
+        tag: [{
+          field: "pageId"
+        }]
+      }
+    });
+
+    const resp = await fetch(searchDataURL);
+    const data = await resp.json();
+    let pageId = 0;
+    for (const route in data) {
+      let pageContent = '';
+      ++pageId;
+      const urlParts = route.split('/').filter(x => x != "" && !x.startsWith('#'));
+
+      let crumb = '';
+      let searchUrl = '/';
+      for (let i = 0; i < urlParts.length; i++) {
+        const urlPart = urlParts[i];
+        searchUrl += urlPart + '/'
+
+        const crumbData = data[searchUrl];
+        if (!crumbData) {
+          console.warn('Excluded page', searchUrl, '- will not be included for search result breadcrumb for', route);
+          continue;
+        }
+
+        let title = data[searchUrl].title;
+        if (title == "_index") {
+          title = urlPart.split("-").map(x => x).join(" ");
+        }
+        crumb += title;
+
+        if (i < urlParts.length - 1) {
+          crumb += ' > ';
+        }
+      }
+
+      for (const heading in data[route].data) {
+        const [hash, text] = heading.split('#');
+        const url = route.trimEnd('/') + (hash ? '#' + hash : '');
+        const title = text || data[route].title;
+
+        const content = data[route].data[heading] || '';
+        const paragraphs = content.split('\n').filter(Boolean);
+
+        sectionIndex.add({
+          id: url,
+          url,
+          title,
+          crumb,
+          pageId: `page_${pageId}`,
+          content: title,
+          ...(paragraphs[0] && { display: paragraphs[0] })
+        });
+
+        for (let i = 0; i < paragraphs.length; i++) {
+          sectionIndex.add({
+            id: `${url}_${i}`,
+            url,
+            title,
+            crumb,
+            pageId: `page_${pageId}`,
+            content: paragraphs[i]
+          });
+        }
+
+        pageContent += ` ${title} ${content}`;
+      }
+
+      window.pageIndex.add({
+        id: pageId,
+        title: data[route].title,
+        crumb,
+        content: pageContent
+      });
+
+    }
+  }
+
+  /**
+   * Performs a search based on the provided query and displays the results.
+   * @param {Event} e - The event object.
+   */
+  function search(e) {
+    const query = e.target.value;
+    if (!e.target.value) {
+      hideSearchResults();
+      return;
+    }
+
+    const { resultsElement } = getActiveSearchElement();
+    while (resultsElement.firstChild) {
+      resultsElement.removeChild(resultsElement.firstChild);
+    }
+    resultsElement.classList.remove('hx:hidden');
+
+    const pageResults = window.pageIndex.search(query, 5, { enrich: true, suggest: true })[0]?.result || [];
+
+    const results = [];
+    const pageTitleMatches = {};
+
+    for (let i = 0; i < pageResults.length; i++) {
+      const result = pageResults[i];
+      pageTitleMatches[i] = 0;
+
+      // Show the top 5 results for each page
+      const sectionResults = window.sectionIndex.search(query, 5, { enrich: true, suggest: true, tag: { 'pageId': `page_${result.id}` } })[0]?.result || [];
+      let isFirstItemOfPage = true
+      const occurred = {}
+
+      for (let j = 0; j < sectionResults.length; j++) {
+        const { doc } = sectionResults[j]
+        const isMatchingTitle = doc.display !== undefined
+        if (isMatchingTitle) {
+          pageTitleMatches[i]++
+        }
+        const { url, title } = doc
+        const content = doc.display || doc.content
+
+        if (occurred[url + '@' + content]) continue
+        occurred[url + '@' + content] = true
+        results.push({
+          _page_rk: i,
+          _section_rk: j,
+          route: url,
+          prefix: isFirstItemOfPage ? result.doc.crumb : undefined,
+          children: { title, content }
+        })
+        isFirstItemOfPage = false
+      }
+    }
+    const sortedResults = results
+      .sort((a, b) => {
+        // Sort by number of matches in the title.
+        if (a._page_rk === b._page_rk) {
+          return a._section_rk - b._section_rk
+        }
+        if (pageTitleMatches[a._page_rk] !== pageTitleMatches[b._page_rk]) {
+          return pageTitleMatches[b._page_rk] - pageTitleMatches[a._page_rk]
+        }
+        return a._page_rk - b._page_rk
+      })
+      .map(res => ({
+        id: `${res._page_rk}_${res._section_rk}`,
+        route: res.route,
+        prefix: res.prefix,
+        children: res.children
+      }));
+    displayResults(sortedResults, query);
+  }
+
+  /**
+   * Displays the search results on the page.
+   *
+   * @param {Array} results - The array of search results.
+   * @param {string} query - The search query.
+   */
+  function displayResults(results, query) {
+    const { resultsElement } = getActiveSearchElement();
+    if (!resultsElement) return;
+
+    if (!results.length) {
+      resultsElement.innerHTML = `<span class="hextra-search-no-result">No results found.</span>`;
+      return;
+    }
+
+    // Highlight the query in the result text.
+    function highlightMatches(text, query) {
+      const escapedQuery = query.replace(/[-\\^$*+?.()|[\]{}]/g, '\\$&');
+      const regex = new RegExp(escapedQuery, 'gi');
+      return text.replace(regex, (match) => `<span class="hextra-search-match">${match}</span>`);
+    }
+
+    // Create a DOM element from the HTML string.
+    function createElement(str) {
+      const div = document.createElement('div');
+      div.innerHTML = str.trim();
+      return div.firstChild;
+    }
+
+    function handleMouseMove(e) {
+      const target = e.target.closest('a');
+      if (target) {
+        const active = resultsElement.querySelector('a.hextra-search-active');
+        if (active) {
+          active.classList.remove('hextra-search-active');
+        }
+        target.classList.add('hextra-search-active');
+      }
+    }
+
+    const fragment = document.createDocumentFragment();
+    for (let i = 0; i < results.length; i++) {
+      const result = results[i];
+      if (result.prefix) {
+        fragment.appendChild(createElement(`
+          <div class="hextra-search-prefix">${result.prefix}</div>`));
+      }
+        let li = createElement(`
+        <li>
+          <a data-index="${i}" href="${result.route}" class=${i === 0 ? "hextra-search-active" : ""}>
+            <div class="hextra-search-title">`+ highlightMatches(result.children.title, query) + `</div>` +
+        (result.children.content ?
+            `<div class="hextra-search-excerpt">` + highlightMatches(result.children.content, query) + `</div>` : '') + `
+          </a>
+        </li>`);
+      li.addEventListener('mousemove', handleMouseMove);
+      li.addEventListener('keydown', handleKeyDown);
+      li.querySelector('a').addEventListener('click', finishSearch);
+      fragment.appendChild(li);
+    }
+    resultsElement.appendChild(fragment);
+    resultsElement.dataset.count = results.length;
+  }
+})();

public/favicon.svg

@@ -0,0 +1,13 @@
+<svg
+   viewBox="0 0 180 180"
+   fill="#1E1E1E"
+   width="180"
+   height="180"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <path
+     fill-rule="evenodd"
+     clip-rule="evenodd"
+     d="m 105.50024,22.224647 c -9.59169,-5.537563 -21.40871,-5.537563 -31.000093,0 L 39.054693,42.689119 C 29.463353,48.226675 23.55484,58.460531 23.55484,69.535642 v 40.928918 c 0,11.07542 5.908513,21.3092 15.499853,26.84652 l 35.445453,20.46446 c 9.591313,5.53732 21.408404,5.53732 31.000094,0 l 35.44507,-20.46446 c 9.59131,-5.53732 15.49985,-15.7711 15.49985,-26.84652 V 69.535642 c 0,-11.075111 -5.90854,-21.308967 -15.49985,-26.846523 z M 34.112797,85.737639 c -1.384445,2.397827 -1.384445,5.352099 0,7.749927 l 24.781554,42.922974 c 1.38437,2.39783 3.942853,3.87496 6.711592,3.87496 h 49.563107 c 2.76905,0 5.3273,-1.47713 6.71144,-3.87496 l 24.78194,-42.922974 c 1.38414,-2.397828 1.38414,-5.3521 0,-7.749927 L 121.88049,42.814746 c -1.38414,-2.397828 -3.94239,-3.874964 -6.71144,-3.874964 H 65.605944 c -2.768739,0 -5.327223,1.477059 -6.711592,3.874964 z"
+     style="stroke-width:0.774993" />
+</svg>

public/images/logo-dark.svg

@@ -0,0 +1,3 @@
+<svg viewBox="0 0 180 180" xmlns="http://www.w3.org/2000/svg" fill="white">
+  <path fill-rule="evenodd" clip-rule="evenodd" d="m 105.50024,22.224647 c -9.59169,-5.537563 -21.40871,-5.537563 -31.000093,0 L 39.054693,42.689119 C 29.463353,48.226675 23.55484,58.460531 23.55484,69.535642 v 40.928918 c 0,11.07542 5.908513,21.3092 15.499853,26.84652 l 35.445453,20.46446 c 9.591313,5.53732 21.408404,5.53732 31.000094,0 l 35.44507,-20.46446 c 9.59131,-5.53732 15.49985,-15.7711 15.49985,-26.84652 V 69.535642 c 0,-11.075111 -5.90854,-21.308967 -15.49985,-26.846523 z M 34.112797,85.737639 c -1.384445,2.397827 -1.384445,5.352099 0,7.749927 l 24.781554,42.922974 c 1.38437,2.39783 3.942853,3.87496 6.711592,3.87496 h 49.563107 c 2.76905,0 5.3273,-1.47713 6.71144,-3.87496 l 24.78194,-42.922974 c 1.38414,-2.397828 1.38414,-5.3521 0,-7.749927 L 121.88049,42.814746 c -1.38414,-2.397828 -3.94239,-3.874964 -6.71144,-3.874964 H 65.605944 c -2.768739,0 -5.327223,1.477059 -6.711592,3.874964 z" style="stroke-width:0.774993" />
+</svg>

public/images/logo.svg

@@ -0,0 +1,3 @@
+<svg viewBox="0 0 180 180" xmlns="http://www.w3.org/2000/svg" fill="currentColor">
+  <path fill-rule="evenodd" clip-rule="evenodd" d="m 105.50024,22.224647 c -9.59169,-5.537563 -21.40871,-5.537563 -31.000093,0 L 39.054693,42.689119 C 29.463353,48.226675 23.55484,58.460531 23.55484,69.535642 v 40.928918 c 0,11.07542 5.908513,21.3092 15.499853,26.84652 l 35.445453,20.46446 c 9.591313,5.53732 21.408404,5.53732 31.000094,0 l 35.44507,-20.46446 c 9.59131,-5.53732 15.49985,-15.7711 15.49985,-26.84652 V 69.535642 c 0,-11.075111 -5.90854,-21.308967 -15.49985,-26.846523 z M 34.112797,85.737639 c -1.384445,2.397827 -1.384445,5.352099 0,7.749927 l 24.781554,42.922974 c 1.38437,2.39783 3.942853,3.87496 6.711592,3.87496 h 49.563107 c 2.76905,0 5.3273,-1.47713 6.71144,-3.87496 l 24.78194,-42.922974 c 1.38414,-2.397828 1.38414,-5.3521 0,-7.749927 L 121.88049,42.814746 c -1.38414,-2.397828 -3.94239,-3.874964 -6.71144,-3.874964 H 65.605944 c -2.768739,0 -5.327223,1.477059 -6.711592,3.874964 z" style="stroke-width:0.774993" />
+</svg>

public/index.html

@@ -0,0 +1,362 @@
+<!DOCTYPE html>
+<html lang="en" dir="ltr"><head>
+	<meta name="generator" content="Hugo 0.160.0"><script src="/livereload.js?mindelay=10&amp;v=2&amp;port=1313&amp;path=livereload" data-no-instant defer></script>
+  <meta charset="utf-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="robots" content="noindex, nofollow" />
+  <link rel="icon shortcut" href="/favicon.ico" sizes="32x32" />
+<link rel="icon" href="/favicon.svg" type="image/svg+xml" id="favicon-svg" />
+<link rel="icon" href="/favicon-16x16.png" type="image/png" sizes="16x16" />
+<link rel="icon" href="/favicon-32x32.png" type="image/png" sizes="32x32" />
+<link rel="apple-touch-icon" href="/apple-touch-icon.png" sizes="180x180" />
+<link fetchpriority="low" href="/site.webmanifest" rel="manifest" />
+<title>CodeJava</title>
+  <meta name="description" content="Learn Java programming" /><link rel="canonical" href="http://localhost:1313/" itemprop="url" />
+
+<meta property="og:title" content="">
+<meta
+  property="og:description"
+  content="
+    
+      Learn Java programming
+    
+  ">
+<meta
+  property="og:type"
+  content="
+    website
+  ">
+<meta property="og:url" content="http://localhost:1313/">
+
+
+  <meta itemprop="name" content="CodeJava">
+  <meta itemprop="description" content="Learn Java programming">
+  <meta name="twitter:card" content="summary">
+  <meta name="twitter:title" content="CodeJava">
+  <meta name="twitter:description" content="Learn Java programming">
+<link href="/css/compiled/main.css" rel="stylesheet" />
+    <link href="/css/variables.css" rel="stylesheet" />
+    <link href="/css/custom.css" rel="stylesheet" />
+
+  
+
+
+  <script>
+    
+
+    function setTheme(theme) {
+      document.documentElement.classList.remove("light", "dark");
+
+      if (theme !== "light" && theme !== "dark") {
+       theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+      }
+
+      document.documentElement.classList.add(theme);
+      document.documentElement.style.colorScheme = theme;
+    }
+
+    setTheme("color-theme" in localStorage ? localStorage.getItem("color-theme") : 'system')
+
+  </script>
+
+  <script>
+    
+
+    if (localStorage.getItem('banner-closed')) {
+      document.documentElement.style.setProperty("--hextra-banner-height", "0px");
+      document.documentElement.classList.add("hextra-banner-hidden");
+    }
+  </script>
+
+  
+  
+  </head>
+<body><div class="hextra-nav-container hx:sticky hx:top-0 hx:z-20 hx:w-full hx:bg-transparent hx:print:hidden">
+  <div
+    class="hextra-nav-container-blur hx:pointer-events-none hx:absolute hx:z-[-1] hx:h-full hx:w-full hx:bg-white hx:dark:bg-dark hx:shadow-[0_2px_4px_rgba(0,0,0,.02),0_1px_0_rgba(0,0,0,.06)] hx:contrast-more:shadow-[0_0_0_1px_#000] hx:dark:shadow-[0_-1px_0_rgba(255,255,255,.1)_inset] hx:contrast-more:dark:shadow-[0_0_0_1px_#fff]"
+  ></div>
+
+  <nav class="hextra-max-navbar-width hx:mx-auto hx:flex hx:items-center hx:justify-end hx:gap-2 hx:h-16 hx:px-6">
+    <a class="hx:flex hx:items-center hx:hover:opacity-75 hx:ltr:mr-auto hx:rtl:ml-auto" href="/">
+    <img class="hx:mr-2 hx:block hx:dark:hidden" src="/images/logo.svg" alt="Logo" height="20" width="20" />
+    <img class="hx:mr-2 hx:hidden hx:dark:block" src="/images/logo.svg" alt="Dark Logo" height="20" width="20" />
+    <span class="hx:mr-2 hx:font-extrabold hx:inline hx:select-none" title="CodeJava">CodeJava</span>
+</a>
+<a
+  title=""
+  href="/courses"
+  
+  class="hx:text-sm hx:contrast-more:text-gray-700 hx:contrast-more:dark:text-gray-100 hx:relative hx:-ml-2 hx:hidden hx:whitespace-nowrap hx:p-2 hx:md:inline-flex hx:items-center hx:gap-1 hx:text-gray-600 hx:hover:text-gray-800 hx:dark:text-gray-400 hx:dark:hover:text-gray-200"
+><span class="hx:text-center">Courses</span>
+</a><div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+<button type="button" aria-label="Menu" class="hextra-hamburger-menu hx:cursor-pointer hx:-mr-2 hx:rounded-sm hx:p-2 hx:active:bg-gray-400/20 hx:md:hidden"><svg height=24 fill="none" viewBox="0 0 24 24" stroke="currentColor"><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 8H20"></path></g><g><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M4 16H20"></path></g></svg></button>
+  </nav>
+</div>
+
+  <div class='hx:mx-auto hx:flex hextra-max-page-width'>
+    <aside class="hextra-sidebar-container hx:flex hx:flex-col hx:print:hidden hx:md:top-16 hx:md:shrink-0 hx:md:w-64 hx:md:self-start hx:max-md:[transform:translate3d(0,-100%,0)] hx:md:hidden hx:xl:block">
+  
+  <div class="hx:px-4 hx:pt-4 hx:md:hidden">
+    <div class="hextra-search-wrapper hx:relative hx:md:w-64">
+  <div class="hx:relative hx:flex hx:items-center hx:text-gray-900 hx:contrast-more:text-gray-800 hx:dark:text-gray-300 hx:contrast-more:dark:text-gray-300">
+    <input
+      placeholder="Search..."
+      class="hextra-search-input hx:focus:hextra-focus hx:block hx:w-full hx:appearance-none hx:rounded-lg hx:px-3 hx:py-2 hx:transition-colors hx:text-base hx:leading-tight hx:md:text-sm hx:bg-black/[.05] hx:dark:bg-gray-50/10 hx:focus:bg-white hx:dark:focus:bg-dark hx:placeholder:text-gray-500 hx:dark:placeholder:text-gray-400 hx:contrast-more:border hx:contrast-more:border-current"
+      type="search"
+      value=""
+      spellcheck="false"
+    />
+    <kbd
+      class="hx:absolute hx:my-1.5 hx:select-none hx:ltr:right-1.5 hx:rtl:left-1.5 hx:h-5 hx:rounded-sm hx:bg-white hx:px-1.5 hx:font-mono hx:text-[10px] hx:font-medium hx:text-gray-500 hx:border hx:border-gray-200 hx:dark:border-gray-100/20 hx:dark:bg-dark/50 hx:contrast-more:border-current hx:contrast-more:text-current hx:contrast-more:dark:border-current hx:items-center hx:gap-1 hx:transition-opacity hx:pointer-events-none hx:hidden hx:sm:flex"
+    >
+      CTRL K
+    </kbd>
+  </div>
+
+  <div>
+    <ul
+      class="hextra-search-results hextra-scrollbar hx:hidden hx:border hx:border-gray-200 hx:bg-white hx:text-gray-100 hx:dark:border-neutral-800 hx:dark:bg-neutral-900 hx:absolute hx:top-full hx:z-20 hx:mt-2 hx:overflow-auto hx:overscroll-contain hx:rounded-xl hx:py-2.5 hx:shadow-xl hx:max-h-[min(calc(50vh-11rem-env(safe-area-inset-bottom)),400px)] hx:md:max-h-[min(calc(100vh-5rem-env(safe-area-inset-bottom)),400px)] hx:inset-x-0 hx:ltr:md:left-auto hx:rtl:md:right-auto hx:contrast-more:border hx:contrast-more:border-gray-900 hx:contrast-more:dark:border-gray-50 hx:w-screen hx:min-h-[100px] hx:max-w-[min(calc(100vw-2rem),calc(100%+20rem))]"
+      style="transition: max-height 0.2s ease 0s;"
+    ></ul>
+  </div>
+</div>
+
+  </div>
+  <div class="hextra-scrollbar hx:overflow-y-auto hx:overflow-x-hidden hx:p-4 hx:grow hx:md:h-[calc(100vh-var(--navbar-height)-var(--menu-height))]">
+    <ul class="hx:flex hx:flex-col hx:gap-1 hx:md:hidden">
+      
+      
+          <li class=""><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/"
+    
+  >Courses
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a><div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/spring-boot/"
+    
+  >Spring Boot
+    </a>
+              
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/"
+    
+  >Introduction to Programming in Java
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/"
+    
+  >Homeworks
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/homeworks/sum/"
+    
+  >Sum
+    </a>
+              
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/"
+    
+  >Lectures
+        <span class="hextra-sidebar-collapsible-button"><svg fill="none" viewBox="0 0 24 24" stroke="currentColor" class="hx:h-[18px] hx:min-w-[18px] hx:rounded-xs hx:p-0.5 hx:hover:bg-gray-800/5 hx:dark:hover:bg-gray-100/5"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M9 5l7 7-7 7" class="hx:origin-center hx:transition-transform hx:rtl:-rotate-180"></path></svg></span>
+    </a>
+              <div class="hx:ltr:pr-0 hx:overflow-hidden">
+        <ul class='hx:relative hx:flex hx:flex-col hx:gap-1 hx:before:absolute hx:before:inset-y-1 hx:before:w-px hx:before:bg-gray-200 hx:before:content-[""] hx:ltr:ml-3 hx:ltr:pl-3 hx:ltr:before:left-0 hx:rtl:mr-3 hx:rtl:pr-3 hx:rtl:before:right-0 hx:dark:before:bg-neutral-800'><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/prog-intro/lectures/intro/"
+    
+  >Lecture 1. Introduction
+    </a>
+              
+            </li></ul>
+      </div>
+            </li></ul>
+      </div>
+            </li><li class="hx:flex hx:flex-col "><a
+    class="hx:flex hx:items-center hx:justify-between hx:gap-2 hx:cursor-pointer hx:rounded-sm hx:px-2 hx:py-1.5 hx:text-sm hx:transition-colors [-webkit-tap-highlight-color:transparent] [-webkit-touch-callout:none] [word-break:break-word]
+      hx:text-gray-500 hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:contrast-more:border hx:contrast-more:border-transparent hx:contrast-more:text-gray-900 hx:contrast-more:hover:border-gray-900 hx:dark:text-neutral-400 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:contrast-more:dark:text-gray-50 hx:contrast-more:dark:hover:border-gray-50"
+    href="/courses/paradigms/"
+    
+  >Paradgims of Programming
+    </a>
+              
+            </li></ul>
+      </div></li>
+    </ul>
+
+    <div class="hx:max-xl:hidden hx:h-0 hx:w-64 hx:shrink-0"></div></div>
+  
+  
+    <div class="hx:md:hidden  hx:sticky hx:bottom-0 hx:max-h-(--menu-height) hx:bg-white hx:dark:bg-dark hx:mx-4 hx:py-4 hx:shadow-[0_-12px_16px_#fff] hx:flex hx:items-center hx:gap-2 hx:border-gray-200 hx:dark:border-neutral-800 hx:dark:shadow-[0_-12px_16px_#111] hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:shadow-none hx:border-t" data-toggle-animation="show"><div class="hx:flex hx:grow hx:flex-col"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+  </ul>
+</div></div></div></aside>
+    
+<nav class="hextra-toc hx:order-last hx:hidden hx:w-64 hx:shrink-0 hx:xl:block hx:print:hidden hx:px-4" aria-label="table of contents">
+    <div class="hextra-scrollbar hx:sticky hx:top-16 hx:overflow-y-auto hx:pr-4 hx:pt-6 hx:text-sm [hyphens:auto] hx:max-h-[calc(100vh-var(--navbar-height)-env(safe-area-inset-bottom))] hx:ltr:-mr-4 hx:rtl:-ml-4">
+      <div class=" hx:sticky hx:bottom-0 hx:flex hx:flex-col hx:items-start hx:gap-2 hx:pb-8 hx:border-gray-200 hx:dark:border-neutral-800 hx:contrast-more:border-t hx:contrast-more:border-neutral-400 hx:contrast-more:shadow-none hx:contrast-more:dark:border-neutral-400">
+        <button aria-hidden="true" id="backToTop" onClick="scrollUp();" class="hx:cursor-pointer hx:transition-all hx:duration-75 hx:opacity-0 hx:text-xs hx:font-medium hx:text-gray-500 hx:hover:text-gray-900 hx:dark:text-gray-400 hx:dark:hover:text-gray-100 hx:contrast-more:text-gray-800 hx:contrast-more:dark:text-gray-50">
+          <span>Scroll to top</span>
+          <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="hx:inline hx:ltr:ml-1 hx:rtl:mr-1 hx:h-3.5 hx:w-3.5 hx:rounded-full hx:border hx:border-gray-500 hx:hover:border-gray-900 hx:dark:border-gray-400 hx:dark:hover:border-gray-100 hx:contrast-more:border-gray-800 hx:contrast-more:dark:border-gray-50">
+            <path stroke-linecap="round" stroke-linejoin="round" d="M4.5 15.75l7.5-7.5 7.5 7.5" />
+          </svg>
+        </button>
+      </div>
+    </div>
+  </nav>
+
+
+    <article class="hx:w-full hx:break-words hx:flex hx:min-h-[calc(100vh-var(--navbar-height))] hx:min-w-0 hx:justify-center hx:pb-8 hx:pr-[calc(env(safe-area-inset-right)-1.5rem)]">
+      <main class="hx:w-full hx:min-w-0 hx:max-w-6xl hx:px-6 hx:pt-4 hx:md:px-12">
+        
+        <div class="content">
+          
+        </div>
+      </main>
+    </article>
+  </div>
+
+      <footer class="hextra-footer hx:bg-gray-100 hx:pb-[env(safe-area-inset-bottom)] hx:dark:bg-neutral-900 hx:print:bg-transparent"><div class="hx:mx-auto hx:flex hx:gap-2 hx:py-2 hx:px-4 hextra-max-footer-width"><div class="hx:flex hx:justify-items-start hx:group" data-theme="light">
+  <button
+    title="Change theme"
+    data-state="closed"
+    data-location="bottom"
+    class="hextra-theme-toggle hx:cursor-pointer hx:rounded-md hx:text-left hx:font-medium hx:h-7 hx:px-2 hx:text-xs hx:hover:bg-gray-100 hx:hover:text-gray-900 hx:dark:hover:bg-primary-100/5 hx:dark:hover:text-gray-50 hx:font-medium hx:text-gray-600 hx:transition-colors hx:dark:text-gray-400 hx:grow"
+    type="button"
+    aria-label="Change theme"
+  >
+    <div class="hx:flex hx:items-center hx:gap-2 hx:capitalize"><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z"/></svg><span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden">Light</span><svg height=12 class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z"/></svg><span class="hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden">Dark</span><svg height=12 class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"  fill="currentColor">
+  <path d="M 11.996094,2 C 6.4986225,2.0192368 2.03125,6.5024993 2.03125,12 c 0,5.497501 4.4673725,9.980763 9.964844,10 H 12 12.0039 c 5.497471,-0.01924 9.964844,-4.502499 9.964844,-10 0,-5.4975007 -4.467373,-9.9807632 -9.964844,-10 H 12 Z M 12,4 c 4.417218,0.017598 7.96875,3.5822356 7.96875,8 0,4.417764 -3.551532,7.982402 -7.96875,8 z" />
+</svg>
+<span class="hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden">System</span></div>
+  </button>
+  <ul
+    class="hextra-theme-toggle-options hx:hidden hx:z-20 hx:max-h-64 hx:overflow-auto hx:rounded-md hx:ring-1 hx:ring-black/5 hx:bg-white hx:py-1 hx:text-sm hx:shadow-lg hx:dark:ring-white/20 hx:dark:bg-neutral-800"
+    style="position: fixed; inset: auto auto 0px 0px; margin: 0px; min-width: 100px;"
+    data-theme="light"
+  >
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="light"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Light
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="dark"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        Dark
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=light]:hidden hx:group-data-[theme=system]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+    <li class="hx:flex hx:flex-col">
+      <p
+        data-item="system"
+        class="hx:text-gray-800 hx:dark:text-gray-100 hx:hover:bg-primary-50 hx:hover:text-primary-600 hx:hover:dark:bg-primary-500/10 hx:hover:dark:text-primary-600 hx:relative hx:cursor-pointer hx:whitespace-nowrap hx:py-1.5 hx:transition-colors hx:ltr:pl-3 hx:ltr:pr-9 hx:rtl:pr-3 hx:rtl:pl-9"
+      >
+        System
+         <span class="hx:absolute hx:inset-y-0 hx:flex hx:items-center hx:ltr:right-3 hx:rtl:left-3 hx:group-data-[theme=dark]:hidden hx:group-data-[theme=light]:hidden"><svg height=1em width=1em xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="2" stroke="currentColor" aria-hidden="true"><path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7"/></svg></span>
+      </p>
+    </li>
+  </ul>
+</div></div><hr class="hx:border-gray-200 hx:dark:border-neutral-800" /><div class="hextra-custom-footer hextra-max-footer-width hx:pl-[max(env(safe-area-inset-left),1.5rem)] hx:pr-[max(env(safe-area-inset-right),1.5rem)] hx:text-gray-600 hx:dark:text-gray-400"></div><div
+      class="hextra-max-footer-width hx:mx-auto hx:flex hx:justify-center hx:py-12 hx:pl-[max(env(safe-area-inset-left),1.5rem)] hx:pr-[max(env(safe-area-inset-right),1.5rem)] hx:text-gray-600 hx:dark:text-gray-400 hx:md:justify-start"
+    >
+      <div class="hx:flex hx:w-full hx:flex-col hx:items-center hx:sm:items-start"><div class="hx:font-semibold"><a class="hx:flex hx:text-sm hx:items-center hx:gap-1 hx:text-current" target="_blank" rel="noopener noreferrer" title="Hextra GitHub Homepage" href="https://github.com/imfing/hextra">
+    <span>Powered by Hextra<svg height=1em class="hx:inline-block hx:ltr:ml-1 hx:rtl:mr-1 hx:align-[-2.5px]" viewBox="0 0 180 180" xmlns="http://www.w3.org/2000/svg" fill="currentColor"><path fill-rule="evenodd" clip-rule="evenodd" d="m 105.50024,22.224647 c -9.59169,-5.537563 -21.40871,-5.537563 -31.000093,0 L 39.054693,42.689119 C 29.463353,48.226675 23.55484,58.460531 23.55484,69.535642 v 40.928918 c 0,11.07542 5.908513,21.3092 15.499853,26.84652 l 35.445453,20.46446 c 9.591313,5.53732 21.408404,5.53732 31.000094,0 l 35.44507,-20.46446 c 9.59131,-5.53732 15.49985,-15.7711 15.49985,-26.84652 V 69.535642 c 0,-11.075111 -5.90854,-21.308967 -15.49985,-26.846523 z M 34.112797,85.737639 c -1.384445,2.397827 -1.384445,5.352099 0,7.749927 l 24.781554,42.922974 c 1.38437,2.39783 3.942853,3.87496 6.711592,3.87496 h 49.563107 c 2.76905,0 5.3273,-1.47713 6.71144,-3.87496 l 24.78194,-42.922974 c 1.38414,-2.397828 1.38414,-5.3521 0,-7.749927 L 121.88049,42.814746 c -1.38414,-2.397828 -3.94239,-3.874964 -6.71144,-3.874964 H 65.605944 c -2.768739,0 -5.327223,1.477059 -6.711592,3.874964 z" style="stroke-width:0.774993" /></svg></span>
+  </a></div></div>
+    </div></footer>
+    
+    <script defer src="/js/main.js" integrity=""></script>
+<script defer src="/js/flexsearch.9f5b5908f93ae86f1ecd4b043b799f580c2d1654e703dd9357d568ac41b2547a.js" integrity="sha256-n1tZCPk66G8ezUsEO3mfWAwtFlTnA92TV9VorEGyVHo=" crossorigin="anonymous"></script>
+        <script defer src="/en.search.js" integrity=""></script>
+  </body>
+</html>

public/index.xml

@@ -0,0 +1,17 @@
+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+  <channel>
+    <title>CodeJava – </title>
+    <link>http://localhost:1313/</link>
+    <description>Recent content on CodeJava</description>
+    <generator>Hugo -- gohugo.io</generator>
+    <language>en</language>
+    
+	  <atom:link href="http://localhost:1313/index.xml" rel="self" type="application/rss+xml" />
+    
+    
+      
+      
+    
+    
+  </channel>
+</rss>

public/js/main.js

@@ -0,0 +1,574 @@
+function computeMenuTranslation(switcher, optionsElement) {
+  // Calculate the position of a language options element.
+  const switcherRect = switcher.getBoundingClientRect();
+
+  // Must be called before optionsElement.clientWidth.
+  optionsElement.style.minWidth = `${Math.max(switcherRect.width, 50)}px`;
+
+  const isOnTop = switcher.dataset.location === 'top';
+  const isOnBottom = switcher.dataset.location === 'bottom';
+  const isOnBottomRight = switcher.dataset.location === 'bottom-right';
+  const isRTL = document.documentElement.dir === 'rtl'
+
+  // Stuck on the left side of the switcher.
+  let x = switcherRect.left;
+
+  if (isOnTop && !isRTL || isOnBottom && isRTL || isOnBottomRight && !isRTL) {
+    // Stuck on the right side of the switcher.
+    x = switcherRect.right - optionsElement.clientWidth;
+  }
+
+  // Stuck on the top of the switcher.
+  let y = switcherRect.top - window.innerHeight - 10;
+
+  if (isOnTop) {
+    // Stuck on the bottom of the switcher.
+    y = switcherRect.top - window.innerHeight + optionsElement.clientHeight + switcher.clientHeight + 4;
+  }
+
+  return { x: x, y: y };
+}
+
+function toggleMenu(switcher) {
+  const optionsElement = switcher.nextElementSibling;
+
+  optionsElement.classList.toggle('hx:hidden');
+
+  // Calculate the position of a language options element.
+  const translate = computeMenuTranslation(switcher, optionsElement);
+
+  optionsElement.style.transform = `translate3d(${translate.x}px, ${translate.y}px, 0)`;
+}
+
+function resizeMenu(switcher) {
+  const optionsElement = switcher.nextElementSibling;
+
+  if (optionsElement.classList.contains('hx:hidden')) return;
+
+  // Calculate the position of a language options element.
+  const translate = computeMenuTranslation(switcher, optionsElement);
+
+  optionsElement.style.transform = `translate3d(${translate.x}px, ${translate.y}px, 0)`;
+}
+
+;
+// Light / Dark theme toggle
+(function () {
+  const defaultTheme = 'system'
+  const themes = ["light", "dark"];
+
+  const themeToggleButtons = document.querySelectorAll(".hextra-theme-toggle");
+  const themeToggleOptions = document.querySelectorAll(".hextra-theme-toggle-options p");
+
+  function applyTheme(theme) {
+    theme = themes.includes(theme) ? theme : "system";
+
+    themeToggleButtons.forEach((btn) => btn.parentElement.dataset.theme = theme );
+
+    localStorage.setItem("color-theme", theme);
+  }
+
+  function switchTheme(theme) {
+    setTheme(theme);
+    applyTheme(theme);
+  }
+
+  const colorTheme = "color-theme" in localStorage ? localStorage.getItem("color-theme") : defaultTheme;
+  switchTheme(colorTheme);
+
+  // Add click event handler to the menu items.
+  themeToggleOptions.forEach((option) => {
+    option.addEventListener("click", function (e) {
+      e.preventDefault();
+
+      switchTheme(option.dataset.item);
+    })
+  })
+
+  // Add click event handler to the buttons
+  themeToggleButtons.forEach((toggler) => {
+    toggler.addEventListener("click", function (e) {
+      e.preventDefault();
+
+      toggleMenu(toggler);
+    });
+  });
+
+  window.addEventListener("resize", () => themeToggleButtons.forEach(resizeMenu))
+
+  // Dismiss the menu when clicking outside
+  document.addEventListener('click', (e) => {
+    if (e.target.closest('.hextra-theme-toggle') === null) {
+      themeToggleButtons.forEach((toggler) => {
+        toggler.dataset.state = 'closed';
+        toggler.nextElementSibling.classList.add('hx:hidden');
+      });
+    }
+  });
+
+  // Listen for system theme changes
+  window.matchMedia("(prefers-color-scheme: dark)").addEventListener("change", () => {
+    if (localStorage.getItem("color-theme") === "system") {
+      setTheme("system");
+    }
+  });
+})();
+
+;
+//
+;
+// Hamburger menu for mobile navigation
+
+document.addEventListener('DOMContentLoaded', function () {
+  const menu = document.querySelector('.hextra-hamburger-menu');
+  const sidebarContainer = document.querySelector('.hextra-sidebar-container');
+
+  function toggleMenu() {
+    // Toggle the hamburger menu
+    menu.querySelector('svg').classList.toggle('open');
+
+    // When the menu is open, we want to show the navigation sidebar
+    sidebarContainer.classList.toggle('hx:max-md:[transform:translate3d(0,-100%,0)]');
+    sidebarContainer.classList.toggle('hx:max-md:[transform:translate3d(0,0,0)]');
+
+    // When the menu is open, we want to prevent the body from scrolling
+    document.body.classList.toggle('hx:overflow-hidden');
+    document.body.classList.toggle('hx:md:overflow-auto');
+  }
+
+  menu.addEventListener('click', (e) => {
+    e.preventDefault();
+    toggleMenu();
+  });
+
+  // Select all anchor tags in the sidebar container
+  const sidebarLinks = sidebarContainer.querySelectorAll('a');
+
+  // Add click event listener to each anchor tag
+  sidebarLinks.forEach(link => {
+    link.addEventListener('click', (e) => {
+      // Check if the href attribute contains a hash symbol (links to a heading)
+      if (link.getAttribute('href') && link.getAttribute('href').startsWith('#')) {
+        // Only dismiss overlay on mobile view
+        if (window.innerWidth < 768) {
+          toggleMenu();
+        }
+      }
+    });
+  });
+});
+
+;
+// Copy button for code blocks
+
+document.addEventListener('DOMContentLoaded', function () {
+  const getCopyIcon = () => {
+    const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
+    svg.innerHTML = `
+      <path stroke-linecap="round" stroke-linejoin="round" d="M8 16H6a2 2 0 01-2-2V6a2 2 0 012-2h8a2 2 0 012 2v2m-6 12h8a2 2 0 002-2v-8a2 2 0 00-2-2h-8a2 2 0 00-2 2v8a2 2 0 002 2z" />
+    `;
+    svg.setAttribute('fill', 'none');
+    svg.setAttribute('viewBox', '0 0 24 24');
+    svg.setAttribute('stroke', 'currentColor');
+    svg.setAttribute('stroke-width', '2');
+    return svg;
+  }
+
+  const getSuccessIcon = () => {
+    const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
+    svg.innerHTML = `
+      <path stroke-linecap="round" stroke-linejoin="round" d="M5 13l4 4L19 7" />
+    `;
+    svg.setAttribute('fill', 'none');
+    svg.setAttribute('viewBox', '0 0 24 24');
+    svg.setAttribute('stroke', 'currentColor');
+    svg.setAttribute('stroke-width', '2');
+    return svg;
+  }
+
+  document.querySelectorAll('.hextra-code-copy-btn').forEach(function (button) {
+    // Add copy and success icons
+    button.querySelector('.hextra-copy-icon')?.appendChild(getCopyIcon());
+    button.querySelector('.hextra-success-icon')?.appendChild(getSuccessIcon());
+
+    // Add click event listener for copy button
+    button.addEventListener('click', function (e) {
+      e.preventDefault();
+      // Get the code target
+      const target = button.parentElement.previousElementSibling;
+      let codeElement;
+      if (target.tagName === 'CODE') {
+        codeElement = target;
+      } else {
+        // Select the last code element in case line numbers are present
+        const codeElements = target.querySelectorAll('code');
+        codeElement = codeElements[codeElements.length - 1];
+      }
+      if (codeElement) {
+        let code = codeElement.innerText;
+        // Replace double newlines with single newlines in the innerText
+        // as each line inside <span> has trailing newline '\n'
+        if ("lang" in codeElement.dataset) {
+          code = code.replace(/\n\n/g, '\n');
+        }
+        navigator.clipboard.writeText(code).then(function () {
+          button.classList.add('copied');
+          setTimeout(function () {
+            button.classList.remove('copied');
+          }, 1000);
+        }).catch(function (err) {
+          console.error('Failed to copy text: ', err);
+        });
+      } else {
+        console.error('Target element not found');
+      }
+    });
+  });
+});
+
+;
+(function () {
+  function updateGroup(container, index) {
+    const tabs = Array.from(container.querySelectorAll('.hextra-tabs-toggle'));
+    tabs.forEach((tab, i) => {
+      tab.dataset.state = i === index ? 'selected' : '';
+      if (i === index) {
+        tab.setAttribute('aria-selected', 'true');
+        tab.tabIndex = 0;
+      } else {
+        tab.removeAttribute('aria-selected');
+        tab.removeAttribute('tabindex');
+      }
+    });
+    const panelsContainer = container.parentElement.nextElementSibling;
+    if (!panelsContainer) return;
+    Array.from(panelsContainer.children).forEach((panel, i) => {
+      panel.dataset.state = i === index ? 'selected' : '';
+      if (i === index) {
+        panel.tabIndex = 0;
+      } else {
+        panel.removeAttribute('tabindex');
+      }
+    });
+  }
+
+  const syncGroups = document.querySelectorAll('[data-tab-group]');
+
+  syncGroups.forEach((group) => {
+    const key = encodeURIComponent(group.dataset.tabGroup);
+    const saved = localStorage.getItem('hextra-tab-' + key);
+    if (saved !== null) {
+      updateGroup(group, parseInt(saved, 10));
+    }
+  });
+
+  document.querySelectorAll('.hextra-tabs-toggle').forEach((button) => {
+    button.addEventListener('click', function (e) {
+      const container = e.target.parentElement;
+      const index = Array.from(container.querySelectorAll('.hextra-tabs-toggle')).indexOf(
+        e.target
+      );
+      
+      if (container.dataset.tabGroup) {
+        // Sync behavior: update all tab groups with the same name
+        const tabGroupValue = container.dataset.tabGroup;
+        const key = encodeURIComponent(tabGroupValue);
+        document
+          .querySelectorAll('[data-tab-group="' + tabGroupValue + '"]')
+          .forEach((grp) => updateGroup(grp, index));
+        localStorage.setItem('hextra-tab-' + key, index.toString());
+      } else {
+        // Non-sync behavior: update only this specific tab group
+        updateGroup(container, index);
+      }
+    });
+  });
+})();
+
+;
+(function () {
+  const languageSwitchers = document.querySelectorAll('.hextra-language-switcher');
+
+  languageSwitchers.forEach((switcher) => {
+    switcher.addEventListener('click', (e) => {
+      e.preventDefault();
+
+      switcher.dataset.state = switcher.dataset.state === 'open' ? 'closed' : 'open';
+
+      toggleMenu(switcher);
+    });
+  });
+
+  window.addEventListener("resize", () => languageSwitchers.forEach(resizeMenu))
+
+  // Dismiss language switcher when clicking outside
+  document.addEventListener('click', (e) => {
+    if (e.target.closest('.hextra-language-switcher') === null) {
+      languageSwitchers.forEach((switcher) => {
+        switcher.dataset.state = 'closed';
+        const optionsElement = switcher.nextElementSibling;
+        optionsElement.classList.add('hx:hidden');
+      });
+    }
+  });
+})();
+
+;
+(function () {
+  const hiddenClass = "hx:hidden";
+  const dropdownToggles = document.querySelectorAll(".hextra-nav-menu-toggle");
+
+  dropdownToggles.forEach((toggle) => {
+    toggle.addEventListener("click", (e) => {
+      e.preventDefault();
+      e.stopPropagation();
+
+      // Close all other dropdowns first
+      dropdownToggles.forEach((otherToggle) => {
+        if (otherToggle !== toggle) {
+          otherToggle.dataset.state = "closed";
+          const otherMenuItems = otherToggle.nextElementSibling;
+          otherMenuItems.classList.add(hiddenClass);
+        }
+      });
+
+      // Toggle current dropdown
+      const isOpen = toggle.dataset.state === "open";
+      toggle.dataset.state = isOpen ? "closed" : "open";
+      const menuItemsElement = toggle.nextElementSibling;
+
+      if (!isOpen) {
+        // Position dropdown centered with toggle
+        menuItemsElement.style.position = "absolute";
+        menuItemsElement.style.top = "100%";
+        menuItemsElement.style.left = "50%";
+        menuItemsElement.style.transform = "translateX(-50%)";
+        menuItemsElement.style.zIndex = "1000";
+
+        // Show dropdown
+        menuItemsElement.classList.remove(hiddenClass);
+      } else {
+        // Hide dropdown
+        menuItemsElement.classList.add(hiddenClass);
+      }
+    });
+  });
+
+  // Dismiss dropdown when clicking outside
+  document.addEventListener("click", (e) => {
+    if (e.target.closest(".hextra-nav-menu-toggle") === null) {
+      dropdownToggles.forEach((toggle) => {
+        toggle.dataset.state = "closed";
+        const menuItemsElement = toggle.nextElementSibling;
+        menuItemsElement.classList.add(hiddenClass);
+      });
+    }
+  });
+
+  // Close dropdowns on escape key
+  document.addEventListener("keydown", (e) => {
+    if (e.key === "Escape") {
+      dropdownToggles.forEach((toggle) => {
+        toggle.dataset.state = "closed";
+        const menuItemsElement = toggle.nextElementSibling;
+        menuItemsElement.classList.add(hiddenClass);
+      });
+    }
+  });
+})();
+
+;
+// Script for filetree shortcode collapsing/expanding folders used in the theme
+// ======================================================================
+document.addEventListener("DOMContentLoaded", function () {
+  const folders = document.querySelectorAll(".hextra-filetree-folder");
+  folders.forEach(function (folder) {
+    folder.addEventListener("click", function () {
+      Array.from(folder.children).forEach(function (el) {
+        el.dataset.state = el.dataset.state === "open" ? "closed" : "open";
+      });
+      folder.nextElementSibling.dataset.state = folder.nextElementSibling.dataset.state === "open" ? "closed" : "open";
+    });
+  });
+});
+
+;
+document.addEventListener("DOMContentLoaded", function () {
+  scrollToActiveItem();
+  enableCollapsibles();
+});
+
+function enableCollapsibles() {
+  const buttons = document.querySelectorAll(".hextra-sidebar-collapsible-button");
+  buttons.forEach(function (button) {
+    button.addEventListener("click", function (e) {
+      e.preventDefault();
+      const list = button.parentElement.parentElement;
+      if (list) {
+        list.classList.toggle("open")
+      }
+    });
+  });
+}
+
+function scrollToActiveItem() {
+  const sidebarScrollbar = document.querySelector("aside.hextra-sidebar-container > .hextra-scrollbar");
+  const activeItems = document.querySelectorAll(".hextra-sidebar-active-item");
+  const visibleActiveItem = Array.from(activeItems).find(function (activeItem) {
+    return activeItem.getBoundingClientRect().height > 0;
+  });
+
+  if (!visibleActiveItem) {
+    return;
+  }
+
+  const yOffset = visibleActiveItem.clientHeight;
+  const yDistance = visibleActiveItem.getBoundingClientRect().top - sidebarScrollbar.getBoundingClientRect().top;
+  sidebarScrollbar.scrollTo({
+    behavior: "instant",
+    top: yDistance - yOffset
+  });
+}
+
+;
+// Back to top button
+
+document.addEventListener("DOMContentLoaded", function () {
+  const backToTop = document.querySelector("#backToTop");
+  if (backToTop) {
+    document.addEventListener("scroll", (e) => {
+      if (window.scrollY > 300) {
+        backToTop.classList.remove("hx:opacity-0");
+      } else {
+        backToTop.classList.add("hx:opacity-0");
+      }
+    });
+  }
+});
+
+function scrollUp() {
+  window.scroll({
+    top: 0,
+    left: 0,
+    behavior: "smooth",
+  });
+}
+
+;
+/**
+ * TOC Scroll - Highlights active TOC links based on visible headings
+ * 
+ * Uses Intersection Observer to track heading visibility and applies
+ * 'hextra-toc-active' class to corresponding TOC links. Selects the
+ * topmost heading when multiple are visible.
+ * 
+ * Requires: .hextra-toc element, matching heading IDs, toc.css styles
+ */
+document.addEventListener("DOMContentLoaded", function () {
+  const toc = document.querySelector(".hextra-toc");
+  if (!toc) return;
+
+  const tocLinks = toc.querySelectorAll('a[href^="#"]');
+  if (tocLinks.length === 0) return;
+
+  const headingIds = Array.from(tocLinks).map((link) => link.getAttribute("href").substring(1));
+
+  const headings = headingIds.map((id) => document.getElementById(decodeURIComponent(id))).filter(Boolean);
+  if (headings.length === 0) return;
+
+  let currentActiveLink = null;
+  let isHashNavigation = false;
+
+  // Create intersection observer
+  const observer = new IntersectionObserver(
+    (entries) => {
+      // Skip observer updates during hash navigation
+      if (isHashNavigation) return;
+
+      const visibleHeadings = entries.filter((entry) => entry.isIntersecting).map((entry) => entry.target);
+
+      if (visibleHeadings.length === 0) return;
+
+      // Find the heading closest to the top of the viewport
+      const topMostHeading = visibleHeadings.reduce((closest, heading) => {
+        const headingTop = heading.getBoundingClientRect().top;
+        const closestTop = closest.getBoundingClientRect().top;
+        return Math.abs(headingTop) < Math.abs(closestTop) ? heading : closest;
+      });
+
+      // Encode the id and make it lowercase to match the TOC link
+      const targetId = encodeURIComponent(topMostHeading.id).toLowerCase();
+      const targetLink = toc.querySelector(`a[href="#${targetId}"]`);
+
+      if (targetLink && targetLink !== currentActiveLink) {
+        // Remove active class from previous link
+        if (currentActiveLink) {
+          currentActiveLink.classList.remove("hextra-toc-active");
+        }
+
+        // Add active class to current link
+        targetLink.classList.add("hextra-toc-active");
+        currentActiveLink = targetLink;
+      }
+    },
+    {
+      rootMargin: "-20px 0px -60% 0px", // Adjust sensitivity
+      threshold: [0, 0.1, 0.5, 1],
+    }
+  );
+
+  // Observe all headings
+  headings.forEach((heading) => observer.observe(heading));
+
+  // Handle direct navigation to page with hash
+  function handleHashNavigation() {
+    const hash = window.location.hash; // already url encoded
+    if (hash) {
+      const targetLink = toc.querySelector(`a[href="${hash}"]`);
+      if (targetLink) {
+        // Disable observer temporarily during hash navigation
+        isHashNavigation = true;
+
+        if (currentActiveLink) {
+          currentActiveLink.classList.remove("hextra-toc-active");
+        }
+        targetLink.classList.add("hextra-toc-active");
+        currentActiveLink = targetLink;
+
+        // Re-enable observer after scroll settles
+        setTimeout(() => { isHashNavigation = false; }, 500);
+        return;
+      }
+    }
+  }
+
+  // Handle hash changes navigation
+  window.addEventListener("hashchange", handleHashNavigation);
+
+  // Handle initial load
+  setTimeout(handleHashNavigation, 100);
+});
+
+;
+// 
+(function () {
+  const faviconEl = document.getElementById("favicon-svg");
+  const faviconDarkExists = "false" === "true";
+
+  if (faviconEl && faviconDarkExists) {
+    const lightFavicon = '/favicon.svg';
+    const darkFavicon = '/favicon-dark.svg';
+
+    const darkModeQuery = window.matchMedia("(prefers-color-scheme: dark)");
+
+    function updateFavicon(e) {
+      faviconEl.href = e.matches ? darkFavicon : lightFavicon;
+    }
+
+    // Set favicon on load
+    updateFavicon(darkModeQuery);
+
+    // Listen for system preference changes
+    darkModeQuery.addEventListener("change", updateFavicon);
+  }
+})();

public/site.webmanifest

@@ -0,0 +1,20 @@
+{
+  "name": "Hextra",
+  "short_name": "Hextra",
+  "start_url": "index.html",
+  "icons": [
+    {
+      "src": "android-chrome-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "android-chrome-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ],
+  "theme_color": "#000000",
+  "background_color": "#000000",
+  "display": "standalone"
+}