class Program

{

public static IEnumerable<long> fib()

{

yield return 0;

long i = 0, j = 1;

while (true)

{

yield return j;

long temp = i;

i = j;

j = temp + j;

}

}

static void Main(string[] args)

{

foreach (long n in fib())

{

if (n > 1000)

break;

Console.WriteLine(n);

}

}

}