using System;
using System.Collections.Generic;

class foo
{
	static void Main ()
	{
		foreach (int i in fib ())
			Console.WriteLine (i);
	}

	static IEnumerable<int> fib ()
	{
		int a = 1, b = 1;

		while (true) {
			yield return a;
			int A = a;

			a = b;
			b = A + b;
		}
	}
}