using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var n = NextNumber();

        var numbers = n.Take(10).ToArray();

        Console.WriteLine(String.Join(", ", numbers));

        Console.WriteLine(n.First().ToString());

        Console.WriteLine(n.First().ToString());

        Console.WriteLine(n.First().ToString());

        Console.WriteLine(n.Take(1).First().ToString());

        Console.WriteLine(n.Take(1).First().ToString());

        Console.WriteLine(n.Take(1).First().ToString());

    }

    private static IEnumerable<int> NextNumber()

    {

        var i = 0;

        while (true)

        {

            yield return i++;

        }

    }

}