using System;

using System.Collections.Generic;

public class Program

{

    static void Main()

    {

        foreach (var i in 10)

        {

            Console.WriteLine(i);

        }

    }

}

​

public static class NumericSequence

{

    public static IEnumerator<int> GetEnumerator(this int input)

    {

        for (int i = input; i >= 0; i--)

        {

            yield return i;

        }

    }

}