# This is how it works:
# resolve(300) # returns "three hundred"
# resolve(210) # returns "two hundred ten"
# and so on...

# Note that this is based on the Brittish system because that is close to my
# native system (Dutch).
# So maybe some American (oriented) people might think it's wrong, but it's
# just no American oriented code.

# Currently, it only takes positive integer numbers.
# That is: $x > 0 && $x / 2 == int($x / 2)


sub resolve {
    my @numbers1 = qw( one two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen twenty );
    my @numbers2 = qw( ten twenty thirty fourty fifty sixty seventy eighty ninety );
    my @numbers3 = qw( thousand million milliard billion billiard trillion trilliard quadrillion quadrilliard quintillion quintilliard sextillion sextilliard septillion septilliard octillion octilliard nonillian nonilliard decillion decilliard );

    my $nr = int $_[0];
    $nr = "$nr";
    $nr =~ s/\D//g;
    $nr = $nr ? $nr : "0";
    if ($nr eq "0") {
        return "";
    }

    my ($smallone, $bigone, $cnr, @allnumbers, $resolve);


    if ($nr < 20) {
        return $numbers1[$nr-1];
    } elsif ($nr < 100) {
        ($nr, $cnr) = $nr =~ m/^(.)(.)$/;
        $smallone = &resolve($cnr);
        $bigone = $numbers2[$nr-1];
        return "$bigone" . ($smallone ? "-$smallone" : "");
    } elsif ($nr < 1000) {
        ($nr, $cnr) = $nr =~ m/^(.)(..)$/;
        $cnr = &resolve($cnr);
        $nr = &resolve($nr);
        return "$nr hundred $cnr";
    } else {
        $nr = reverse $nr;
        $nr =~ s/(\d{3})/$1 /g;
        $nr = reverse $nr;
        @allnumbers = split(" ", $nr);
        while (@allnumbers) {
            $cnr = shift @allnumbers;
            $bigone = &resolve($cnr);
            if ($#allnumbers > -1 && $cnr > 0) {
                $bigone .= " $numbers3[$#allnumbers] ";
            }
            $resolve .= $bigone;
            
        }
        return $resolve;
    }
}