#!/usr/bin/perl

use strict;
use warnings;

if (@ARGV < 2) {
	print STDERR "Usage: $0 <oldfile> <newfile>\n";
	exit 2;
}

open OLD, '<', $ARGV[0] or die "E: couldn't open old list: $!";

my @old_packs = <OLD>;
my %old_packs;

foreach (@old_packs) {
	chomp;
	$old_packs{$_}++;
}

close OLD or warn "couldn't close old list: $!\n";

open NEW, '<', $ARGV[1] or die "E: couldn't open new list: $!";

my @new_packs = <NEW>;
my %new_packs;

foreach (@new_packs) {
	chomp;
	$new_packs{$_}++;
}

foreach (keys %old_packs) {
	delete $new_packs{$_};
}

close NEW or warn "couldn't close new list: $!\n";

print join "\n", sort keys %new_packs;