using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var hashSet1 = new HashSet<int>();

​

        // Initialize the set using object initialization syntax 

        var hashSet = new HashSet<int>() { 1, 2, 3, 4, 5, 6, 7, 8 };

        foreach(int v in hashSet)

            Console.Write(v + " ");

        Console.WriteLine();

        // Add an object to the set

        hashSet.Add(4);

        hashSet.Add(9);

        foreach(int v in hashSet)

            Console.Write(v + " ");

        Console.WriteLine();

        // Check to see if the set contains an object 

        var contains = hashSet.Contains(1);

        Console.WriteLine(contains);

        // Return the number of objects in the set 

        var count = hashSet.Count;

        Console.WriteLine(count);

        var another = new HashSet<int>(){1, 3, 5, 7, 9};

        // Modify the set to include only the objects present in the set and the other set

        hashSet.IntersectWith(another);

        foreach(int v in hashSet)

            Console.Write(v + " ");

        Console.WriteLine();

        another = new HashSet<int>(){1, 3, 5};

        // Remove all objects in "another" set from "hashSet" 

        hashSet.ExceptWith(another);

        foreach(int v in hashSet)

            Console.Write(v + " ");

        Console.WriteLine();

​

        another = new HashSet<int>(){2, 4, 6};

        // Modify the set to include all objects included in itself, in "another" set, or both

        hashSet.UnionWith(another);

        foreach(int v in hashSet)

            Console.Write(v + " ");

        Console.WriteLine();

​

        var isSupersetOf = hashSet.IsSupersetOf(another);

        Console.WriteLine(isSupersetOf);

        var isSubsetOf = hashSet.IsSubsetOf(another);

        Console.WriteLine(isSubsetOf);

        var equals = hashSet.SetEquals(another);

        Console.WriteLine(equals);

        // Remove an object 

        hashSet.Remove(4);

        foreach(int v in hashSet)

            Console.Write(v + " ");

        Console.WriteLine();

        // Remove all objects 

        hashSet.Clear();

        foreach(int v in hashSet)

            Console.Write(v + " ");

        Console.WriteLine();

    }

}