https://mirror.codeforces.com/contest/1148/submission/88665764 .Runtime error in https://mirror.codeforces.com/contest/1148/problem/D . I cannot figure out why there is runtime error, inspite of such low memeory being used. All the values are distinct in the problem.

https://mirror.codeforces.com/blog/entry/77846 Can anyone explain why in problem G we are having a cyclic shift as d where (d.n)%m=0? I seem to get a bit of the intuitive picture but a proper formal proof would be appreciated.

https://mirror.codeforces.com/contest/1366/submission/83422255 In today's contest i was trying to solve a problem and i got re. Can anyone explain why?