Today's problem B : https://codeforces.net/contest/652/problem/C
Isn't it the case of stealing/copying a problem? The problem statement was changed only, the problem remains completely the same.
So will it be unrated? Or the copying rule was only for Indian authors?
Problem in general is very well known. If we unrate every contest which had reused ideas for A or B, half of the contests will be unrated
these 2 problems are not the same cuz the input of 1771B does not contain a permutation, and the code of solutions of 652C can not pass 1771B directly.