So i was just going through all subs of problem C for trying hacks and found some highly similar submissions made during contest time.
Same code with just variable names altered, and covered by a lot of unused boilerplate code possibly to escape detector? I think it is a case of plagiarism. I have not seen their codes of other problems, so there might be something of interest there as well.
MikeMirzayanov Please look into this and take necessary action.