Chef and Intersection Line

Chef is playing a game that lasts M seconds. She has a matrix A[M][N][N] which contains a single integer in each of the M * N * N cells. For each k such that 1 ≤ k ≤ M, on the k-th second, she chooses some pair (i, j) such that 1 ≤ i, j ≤ N. This will fetch her A[k][i][j] points. She also has a 2-D Cartesian plane which is empty initially. Then for each second k, where k > 1, she will draw a line