# USACO 2019 US February Silver Problem 2

In the editorial because I couldn’t figure out how to solve the problem. I don’t understand why you would set the corners to -1.
Block Spoilers

Suppose you have a 7\times 7 array.

0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0


Suppose you paint from (1,1), (5,5). These are the corners of the square.
According to the editorial, it would be

0 0 0 0 0 0 0
0 1 0 0 0 -1 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 -1 0 0 0 1 0
0 0 0 0 0 0 0


Applying the prefix sum,

0 0 0 0 0 0 0
0 1 1 1 1 0 0
0 1 1 1 1 0 0
0 1 1 1 1 0 0
0 1 1 1 1 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0


But, shouldn’t it be

0 0 0 0 0 0 0
0 1 1 1 1 1 0
0 1 1 1 1 1 0
0 1 1 1 1 1 0
0 1 1 1 1 1 0
0 1 1 1 1 1 0
0 0 0 0 0 0 0


So then, the answer will be wrong because the program will output 16 instead of 25?

Edit: Nevermind. I figured out that the points they give are coordinates.