using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var items = new int[] 

        { 

            3, 4, 2, 1, 5, 

            3, 4, 2, 1, 5, 

            3, 4, 2, 1, 5, 

            3, 4, 2, 1, 5,   

        };

        var hasSet = new HashSet<int>(items);

        Console.WriteLine("Items count: {0}", items.Count());

        Console.WriteLine("HashSet count: {0}", hasSet.Count());

        foreach(var hash in hasSet)

            Console.WriteLine(hash);

    }

}