1use integer; 2 3sub Ack { 4 return $_[0] ? ($_[1] ? Ack($_[0]-1, Ack($_[0], $_[1]-1)) 5 : Ack($_[0]-1, 1)) 6 : $_[1]+1; 7} 8 9my $NUM = 9; 10$NUM = 1 if ($NUM < 1); 11my $ack = Ack(3, $NUM); 12