In CodeForces, I posted a tutorial on how to count the number of empty subgrids in a grid because I couldn’t find any tutorial for this specific problem online and it has a score of -13 with no hate comments.

Did I somehow mess up with my algorithm? I am pretty sure it is correct since I have tested it with a few examples and I also solved CHSGMNTS with this algorithm. Therefore, I do not understand how this post got -13 on CodeForces. Did I mess up with my algorithm here or are people on CodeForces just really mean and downvote a lot for no good reason?