public class MainClass 
                  { 
                  public static void Main() 
                  { 
                  Console.WriteLine(Foo(30)); 
                  } 
                  public static int Foo(int i) 
                  { 
                  if (i <= 0) 
                  return 0; 
                  else if(i > 0 && i <= 2) 
                  return 1; 
                  else return Foo(i -1) + Foo(i - 2); 
                  } 
                  }