using System;
using System.Collections.Generic;
 
class ProgrammingLanguagesHashSet
{
    static void Main()
    {
        Console.WriteLine("Programming Languages HashSet Demo:");
        Console.WriteLine("===================================");
 
        // Create HashSets for different programming paradigms
        HashSet<string> webLanguages = new HashSet<string>();
        HashSet<string> systemLanguages = new HashSet<string>();
 
        // Add web development languages
        webLanguages.Add("JavaScript");
        webLanguages.Add("TypeScript");
        webLanguages.Add("PHP");
        webLanguages.Add("Python");
        webLanguages.Add("Ruby");
        webLanguages.Add("JavaScript"); // Try to add duplicate - will be ignored
 
        Console.WriteLine("Web Development Languages:");
        Console.Write("webLanguages contains {0} elements: ", webLanguages.Count);
        DisplayHashSet(webLanguages);
 
        // Add system programming languages
        systemLanguages.Add("C");
        systemLanguages.Add("C++");
        systemLanguages.Add("Rust");
        systemLanguages.Add("Go");
        systemLanguages.Add("Python"); // Python appears in both sets
 
        Console.WriteLine("System Programming Languages:");
        Console.Write("systemLanguages contains {0} elements: ", systemLanguages.Count);
        DisplayHashSet(systemLanguages);
 
        // Test adding duplicate
        bool wasAdded = webLanguages.Add("PHP");
        Console.WriteLine("\nTrying to add PHP again to webLanguages: " + wasAdded);
 
        // Create a union of both sets
        HashSet<string> allLanguages = new HashSet<string>(webLanguages);
        Console.WriteLine("\nCreating union of web and system languages...");
        allLanguages.UnionWith(systemLanguages);
 
        Console.Write("allLanguages (union) contains {0} elements: ", allLanguages.Count);
        DisplayHashSet(allLanguages);
 
        // Find intersection (languages common to both sets)
        HashSet<string> commonLanguages = new HashSet<string>(webLanguages);
        commonLanguages.IntersectWith(systemLanguages);
 
        Console.Write("\nCommon languages (intersection) contains {0} elements: ", commonLanguages.Count);
        DisplayHashSet(commonLanguages);
 
        // Find languages only in web development (difference)
        HashSet<string> webOnlyLanguages = new HashSet<string>(webLanguages);
        webOnlyLanguages.ExceptWith(systemLanguages);
 
        Console.Write("\nWeb-only languages (difference) contains {0} elements: ", webOnlyLanguages.Count);
        DisplayHashSet(webOnlyLanguages);
 
        // Test subset relationship
        HashSet<string> scriptingLanguages = new HashSet<string> {"JavaScript", "Python"};
        Console.WriteLine("\nIs scriptingLanguages a subset of webLanguages? " + 
                         scriptingLanguages.IsSubsetOf(webLanguages));
    }
 
    private static void DisplayHashSet(HashSet<string> set)
    {
        Console.Write("{ ");
        foreach (string language in set)
        {
            Console.Write(language + " ");
        }
        Console.WriteLine("}");
    }
}