In the recent round 671 for Div.2 problem A was rated 900 and B was 1200. I wonder how this was calculated? The round clearly showed that less than half of the registered participants tried to solve A. Even less solved it. Much less attempts for solving B. Do you actually estimate the amount of code the problem requires to write? Or the amount of reasoning? To me, even if you think that the problem is easy but you put quite a tricky problem statement then the problem is harder than it was planned to be. If you estimate the problem by the number of red-like coders solving it then it is not really faire as the real participants are mostly blue-like coders and the numbers may differ there.