#!/usr/bin/perl

use strict;
use warnings;

$#ARGV == 1 or die "USAGE: dudiff.pl <OLD_DU_FILE> <NEW_DU_FILE>";

my %old;
open my $fh, '<', $ARGV[0] or die;
while (<$fh>) {
    /^([0-9]+)[ \t]+(.*)$/ or die;
    $old{$2} = $1;
}
close $fh;

my %change;
open $fh, '<', $ARGV[1] or die;
while (<$fh>) {
    /^([0-9]+)[ \t]+(.*)$/ or die;
    $change{$2} = $1 - ($old{$2} // 0);
}
close $fh;

foreach my $file (keys %old) {
    if (! exists $change{$file}) {
        $change{$file} = - $old{$file};
    }
}

foreach my $file (sort {$change{$b} <=> $change{$a}} keys %change) {
    printf "%d\t%s\n", $change{$file}, $file;
}