using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        Fibonacci().Take(10).Dump();

    }

    static IEnumerable<int> Fibonacci()

    {

        int a = 0,  b = 1;

        for(;;)  {        

            yield return a;

            int n = a;

            a += b;

            b = n;          

        }

    }

}