#!/usr/bin/perl
use strict;
use warnings;
use LWP::Simple;

my $page = get($ARGV[0]) or die "unable to get page\n";
my @images = ( $page =~ /http:\/\/images\.4chan\.org\/wg\/src\/\d+\.jpg/g );

foreach (uniq(@images)){
    $_ =~ /(\d+\.jpg)/;
    unless (-e $1){
        system("wget $_");
    }
}
sub uniq {
    return keys %{{ map { $_ => 1 } @_ }};
}