I got two solutions for http://codeforces.com/contest/1036/problem/F

First one: 42893786 Second one: 42893945

First solution gets MLE, though it differs from second one only in line 81. On this line in first approach I try to use precalculated values from the array, instead of calculating them anew.

Can someone explain how a person can get MLE because of trying to get a value from an array?