sub tony_UCS {
  local $_ = reverse shift;
  my $longest = my $tohere = "";
  while (my $char = chop $_) {
    my $idx = index($tohere, $char);
    if ($idx != -1) {
      $longest = $tohere if (length $tohere > length $longest);
      $tohere = substr($tohere, $idx + 1) . $char;
    } else {
      $tohere .= $char;
    }
  }
  $longest = $tohere if (length $tohere > length $longest);
  return $longest;
}