I submitted this 311120546 solution to the recent contest Educational Codeforces Round 176 (Rated for Div. 2).

I was pretty sure my solution is N^2, and I didn't see a reason why it should TLE. Right after submitting I was a bit surprised that the solution took like 1.5s but I thought whatever, there's no way it gets TLE.

How come this code takes over 2s? The only explanation I can see is that the iteration over multiset is not linear which is what I thought for quite a long time.