Solution Link of number C question https://youtu.be/PK27JkDUq58
Some cheater:
https://mirror.codeforces.com/contest/1822/submission/203341284
https://mirror.codeforces.com/contest/1822/submission/203341760
https://mirror.codeforces.com/contest/1822/submission/203337437
https://mirror.codeforces.com/contest/1822/submission/203339721
https://mirror.codeforces.com/contest/1822/submission/203337206
MikeMirzayanov take action against them.