using System;
using System.Collections.Generic;

public class Test
{
	static IEnumerable<int> infinite(int step = 1, int start = 0)
	{
		while (true)
			yield return start += step;
	}
	
	public static void Main()
	{
		foreach (var i in infinite(2, 13))
		{
			if (i > 42)
				break;
			Console.WriteLine(i);
		}
	}
}