# thanks to: mr_mischief for help and efficient isPrime() rewrite.

sub isPrime {
    my $num = $_[0];
    my $val = 'prime';
    if ($num =~ /^\d+$/ && $num >= 2) {
        my $mod = 2;
        my $div = int($num / 2);
        while ($mod <= $div) {
            ($num % $mod) == 0 ? ($val = 'composite', last) : $mod++;
        }
    } else { $val = 'neither'; }
    print ' ' . $num . ":\t\t$val\n";
}

# rz/021005