https://codeforces.me/contest/1684/submission/157727918
this is my code for case 1 5 1 1 2 3 4 5
my code outputs 4 and the answer is 0 because you can move 5 to 0 yet, my code passed systest. in my code, if some number is maximum MEX and is given as input, it can't be detected as MEX.
i mean...this was very strange experience in my codeforces life.