Maximum Sum Square SubMatrix

Given a 2D integer matrix A of size N x N find a B x B submatrix where B<= N and B>= 1, such that sum of all the elements in submatrix is maximum.

1 <= N <= 10³.

1 <= B <= N

-10² <= A[i][j] <= 10².

First arguement is an 2D integer matrix A.

Second argument is an integer B.

Return a single integer denoting the maximum sum of submatrix of size B x B.

Input 1:

 A = [
        [1, 1, 1, 1, 1]
        [2, 2, 2, 2, 2]
        [3, 8, 6, 7, 3]
        [4, 4, 4, 4, 4]
        [5, 5, 5, 5, 5]
     ]
 B = 3

Input 2:

 A = [
        [2, 2]
        [2, 2]
    ]
 B = 2

Output 1:

 48

Output 2:

 8

Explanation 1:

    Maximum sum 3 x 3 matrix is
    8 6 7
    4 4 4
    5 5 5
    Sum = 48

Explanation 2:

 Maximum sum 2 x 2 matrix is
  2 2
  2 2
  Sum = 8