The code below getting runtime error in 173888643 codeforces after submission but runs okay in vs code. Can anyone kindly help why is this code getting runtime error?

How is the brightness calculated for the pyramid? I understand the calculation for all the rooms. But room (5, 2) is not clear. Also in the explanation of test case 3, how the brightness of room (3, 2) is 3? Here is the problem link : Round #822 B.