i think you can try to write without using two def.

Do NOT have global variables, without resetting them. (diff in this case) Either reset it every function call, or put it inside the function (better way).

You can read through this FAQ and try to find something helpful. If you can't find anything, you can post your code for us to check (see here how to post it).

But did you check it with random tests?

hobovsky is just asking if you used the exact same input values in your local environment as those basic tests listed here on Code Wars.

Do you test it locally with exactly the same input it fails on CW?