Hi, johngg -

I like the approach of back-referencing the match from the look-behing ... the only issue I have with the code you propose is that it over-generates in the sense that it will also pass strings all other strings that do not match the regex like 'stp' ... and that, of course, it shouldn't since we only want words to pass that have a non-double vowels in front of the word-terminal 'p'.