The editorial is empty. Don't waste your submission on it.

This is a very poor puzzle, for the simple reason that there does not seem to be an elegant solution for it. Just brute-force it.

So the solution is very easy, but the implementation is very tedious and boring.

marked as medium with only 30 points, are you kidding :/

In some test cases, they use "X" in place of "+". These is not consistent

If people didn't got the clue, then this one is hard. I personally think this one is hard.