Hi, guys! In the problem statement input is a string, that consists of a..z or A..Z.
Let me guess, Test 7 has some other chars ? If so, please, correct prom statement with this note.
4 my submissions were with WA#7 until I added char check

Test 7 consists of characters a..z and A..Z only.

I had the same situation as topic starter. Maybe there is '\n' at the end of the test #7.