I was trying to solve this problem (http://mirror.codeforces.com/contest/56/problem/E). I am stuck on Test Case 30.(Link to my submission 58845497). I tried for hours but not been able to find my mistake. My algorithm is same as the editorial given, but it is giving wrong answer verdict on test case 30. Please help me in debugging the code, and also share some debugging technique, what you use during a contest.