Two words are considered “friendly” if there exists a one to one mapping of letters between the two.
GAGA and BOBO are friendly because mapping G<->B and A<->O would make them the same.
HHHH and BOBO are not friendly. Neither are JKKJ and JKKJJ.
… contains 5 words that have at least one friend. How many words are there in the list with at least one friend?