I don't think that there's any way to match a string at a particular location in the Subject. That said, if you just want to filter emails that contain both (instead of either) of those strings, you can set up a pair of rules. One rule matches against one of the strings, and if it finds it, it sets a category. The second rule matches against both the string and the category, and does whatever it is that you want to do with the email. You might want a third rule to clear that category on half-matches.