An announcement string s may emphasize letters by repeating them. A word is stretchable when it can become exactly s by adding letters to existing consecutive groups. An added group must finish with at least three equal letters.

Count the stretchable words in words. Letters cannot be removed, reordered, or changed. Every word uses lowercase English letters. Compare matching consecutive letter groups. A group in s of size one or two cannot change size. A group of size at least three may absorb repetitions, provided the word group is no longer than it.