use strict;
use warnings;
use Math::BigInt;
no warnings 'recursion';
my $iter = 0;

my ($c, $d) = @ARGV;
print "ackermann ( $c, $d) = ", acker($c, $d), "\n";

sub acker {
	my ($i, $j) = @_;
	$iter++;
	print "Iteration $iter: i = $i, j = $j \n";
	return if $iter >= 40;
	return 2**$j if $i <= 1;
	return acker( $i-1, 2) if $j <= 1;
	return acker ($i - 1, acker ($i, $j - 1));
}