for (split(/:/, $$pattern)) {
    $_ = 'S0' . $_ unless /^S/;
    $_ .= 'S0' unless /S\d+$/;
    print STDERR "pattern: $_\n";
    my @pieces = split(/[SF](\d+)/, $_);
    foreach my $count (0..$#pieces) {
        print STDERR "$count -> [$pieces[$count]] ";
    }
    print STDERR "\n";
}