AoC day 13 (pt1), Perl

#!/usr/bin/perl

use strict;
use warnings;

my $time  = <>; chomp $time;
my @buses = grep { $_ ne 'x' } map { chomp; split /,/ } <>;
my %next  = map { $_ => ($_ - $time % $_) } @buses;

my $part1;
foreach my $k (sort { $next{$a} <=> $next{$b} } keys %next) {
    $part1 //= $k * $next{$k};
}

print "Part 1: $part1\n";