#ex_08-3
#Learning Perl Appendix A, Exercise 8.3
sub card {
    my %card_map;
    @card_map{0..9} = qw(
        zero one two three four five six seven eight nine
    );
    my($num) = @_;
    my($negative);
    if ($num < 0) {
        $negative = "negative ";
        $num = - $num;
    }
    if ($card_map{$num}) {
        return $negative . $card_map{$num};
    } else {
        return $negative . $num;
    }
}