On 29 January 2020, Educational Codeforces Round 103 (Rated for Div. 2) Educational round 103 was conducted. Problem A was solved correctly in the contest by me, used[submission:105914510]. At the time of the hacking, it was hacked. Now, what is special about this. The thing is that the problem setter should have included varieties of the test case in the system test cases because the test case at which my solution failed was a very common one that should have been included. The mistake is mine, that I should have kept the complexity in mind, but why it got accepted in the first place.

If possible MikeMirzayanov try to include various types of test cases in the system test case so that they should not get accepted in the first place if the solution is faulty, so that the user can work on them in the contest itself.