Last two rounds went really bad for me. I got FST on C in round 791 (a silly mistake that MUST not even pass test case 2), but that was okay for me. Then comes the round 792, I got FST on both C and D. yeah!! I was pretty sad but today I was upsolving D with a different approach. I knew that my approach was wrong but I still got AC. I came up with a hack test case for my wrong code. Someone please hack my submission. Test case is:

1
6 5
4 1 100 100 1 1

This is giving 4 for my solution 157830344 which is clearly incorrect.

It's really bad that none of those 77 cases included such a small observable test case. I request authors to make at least system tests stronger if not pretests.