A 3 x 3 magic square is a 3 x 3 grid filled with distinct numbers from 1 to 9 such that each row, column, and both diagonals all have the same sum. Given a row x col grid of integers, how many 3 x 3 "magic square" subgrids are there? (Each subgrid is contiguous). Example 1: Input: grid = [[4,3,8,4],[9,5,1,9],[2,7,6,2]] Output: 1 Explanation: The following subgrid is a 3 x 3 magic square: while this one is not: In total, there is only one magic square inside the given grid. Example 2: Input: grid = [[8]] Output: 0 Example 3: Input: grid = [[4,4],[3,3]] Output: 0 Example 4: Input: grid = [[4,7,8],[9,5,1],[2,3,6]] Output: 0 Constraints: row == grid.length col == grid[i].length 1 <= row, col <= 10 0 <= grid[i][j] <= 15