Solution Link of number C question https://youtu.be/PK27JkDUq58
Some cheater:
https://codeforces.me/contest/1822/submission/203341284
https://codeforces.me/contest/1822/submission/203341760
https://codeforces.me/contest/1822/submission/203337437
https://codeforces.me/contest/1822/submission/203339721
MikeMirzayanov take action against them.