hi https://mirror.codeforces.com/contest/1972/submission/258916012 https://mirror.codeforces.com/contest/1972/submission/258916865 they have cheated on same time and same code!(Q-D) please check https://mirror.codeforces.com/contest/1972/submission/258922220 https://mirror.codeforces.com/contest/1972/submission/258916012 and (Q-C)