About a submission that i have made in code forces

Question

In the same problem at first I submitted this solution: https://codeforces.com/contest/1620/submission/142528587
then the only thing that I changed is that I included usigned long long int and the results changed drastically why??
second code:
https://codeforces.com/contest/1620/submission/142528959

Answer 1

If any of the difference calculations should result in a negative number, then it will cause an underflow in the unsigned version and the max() results will be quite different.