my @files = map {&makefiles} @in;

sub
makefiles
{
    my ($count, $file) = split;

    $file =~ s/^$in_prefix//;

    my ($campaign, $month, $fname) = split /\//, $file;

    return {        # not strictly necessary, but *readable*
        campaign => $campaign,
        month => $month,
        file => $fname,
        count => $count,
        sort => "$campaign:$month:$file"
    };
}