using System;

def args = Environment.GetCommandLineArgs ();
def n = if (args.Length < 2) 1 else int.Parse (args [1]);

def Ack (M, N) {
  if (M == 0) N + 1
  else if (N == 0) Ack (M - 1, 1)
  else Ack (M - 1, Ack (M, (N - 1)))
}

Console.WriteLine ($ "Ack(3,$n): $(Ack (3, n))");