How problem setters creats strong test cases for problem.I want to know their strategy.I hope this will help me when I get Wa,TLE,MLE in contest. I also want to be a good problem setter (but I am not skilled enough now).So I want to practice creating critical test cases for problems.I hope this will help me in contest as well as when I will start to set problems in contest in different oj.(If My Allah wants).