#!/usr/bin/perl

use strict;
use warnings;


my @allTags;

{   local @ARGV = <[0-9][0-9][0-9][0-9].txt>;

    my %uniqueTags;
    while ( my $line = <> ) {
        next unless $line =~ s/^tags\s+//;
        $line =~ s/\s+\z//;
        $uniqueTags{ $_ } = 1 for split /\s+,\s+/, $line;
        }

    @allTags = keys %uniqueTags;
    }

print "@allTags\n";