link to my submission — https://mirror.codeforces.com/contest/463/submission/86461525 Basically I first calculated the sums of all the diagonals. Then through observations figured out that one bishop needs to be placed at row and column with even sum(let say white square) and other at the black square. So I thought the answer must be max of white sq sum+ max(black square sum) and then minus the square at which they both intersect. I can't figure out where this goes wrong