I feel really disappointed after todays Codeforces Round 741 (Div. 2) because of very strong samples in 1562D1 - Two Hundred Twenty One (easy version).

• the fact that answer is always <= 2 is not so obvious, but samples made it clear.

• samples also made it clear that answer is depends on parity of the sign-variable sum

I know a lot of people (including myself) who did not prove it at all. I think problem solving is not about just getting Accepted by staring at samples, but analysing problem and come up with ideas. I spent more time analysing problem A and I don't think it is right