// $Id: ackermann.csharp,v 1.0 2002/02/14 10:58:00 dada Exp $
// http://dada.perl.it/shootout/

using System;

class App {

    public static int Ack(int M, int N) {
        if (M == 0) return( N + 1 );
        if (N == 0) return( Ack(M - 1, 1) );
        return( Ack(M - 1, Ack(M, (N - 1))) );
    }
    
    public static int Main(String[] args) {
        int n;
        n = System.Convert.ToInt32(args[0]);
        if(n < 1) n = 1;
    
        Console.WriteLine("Ack(3," + n.ToString() + "): " + System.Convert.ToString(Ack(3, n)) + "\n");
        return(0);
    }
}