I know many people think the problems are bad and want the contest unrated. I lost GM from this round too. But I think the problems are somehow ok. FSTs on A is avoidable, and using long long is actually very obvious. More low rated users FSTed than high rated users, so this is ok and I consider it as part of the problem. BCDEF are good(though I didn't solve E, and also I ignored m<=5000 in F). I know the std for G was wrong at first, but it's fixed quickly, which isn't a big problem. H would also be a good problem, if there isn't oeis. I noticed that many people had passed H when I was doing E, so I tried H in the last 1h. I nearly got the formula in the contest.

Though I still think that authors should at least try to check on oeis before having problems like this, and they should also check for integer overflows for every problem.

Hope to reach GM soon and good luck for everyone :)