I was trying to solve Problem B from previous contest — round 976 div2. My solution is failing a testcase, its NOT TLE. Initially I thought maybe its due to Integer or Long overflow. To make sure I am not making any implementation errors, I even tried used the exact same code as given in editorial, still my code is failing testcase 8. Am I missing something, I tried reading other java solutions, but I think they encountered same problems, that's why most people used different approach while solving in java.

I am implementing the Code 1 of problem B in editorial.
Problem Link — https://mirror.codeforces.com/contest/2020/problem/B
Link to editorial — https://mirror.codeforces.com/blog/entry/134516
Link to my submission — https://mirror.codeforces.com/contest/2020/submission/284059093