AoC day 2, Perl

#!/usr/bin/perl

use strict;
use warnings;

my $horz  = 0;
my $aim   = 0;
my $depth = 0;

while (<>) {
    my ($cmd, $mag) = split;

    if ($cmd eq 'forward') {
        $horz  += $mag;
        $depth += $mag * $aim;
    } else {
        # Evil! level just happens to be a word between up and down
        $aim += ('level' cmp $cmd) * $mag;
    }
}

print "Part 1: ", $horz * $aim,   "\n";
print "Part 2: ", $horz * $depth, "\n";