sub inclusive {
  my ($big, $little) = @_;
  $big =~ join(
    '',
    map { "(?=.*" . join('.*', @$_) . ")" }
    map { ++$i & 1 ? [ map quotemeta, split // ] : () }
    join('', sort split //, $little) =~ /((.)\2*)/gs;
  );
}