Hello people of Codeforces,

I really hate problems with too many edge cases or difficult implementation, so I've been avoiding such problems for far too long. Because of that I am really bad with casework and implementation. Most of the time I can come up with solutions but fail to implement them before the timer runs out on me. So I have decided to suffer through such problems to improve my casework and implementation skills.

So give me the worst problems you have seen, problems with cruel edge cases or a cruel number of cases or problems with implementation much more difficult than their logic. Do your worst.

Also share any implementation tricks you have for the problem with