Given a m x n matrix grid which is sorted in non-increasing order both row-wise and column-wise, return the number of negative numbers in grid. Example 1: Input: grid = [[4,3,2,-1],[3,2,1,-1],[1,1,-1,-2],[-1,-1,-2,-3]] Output: 8 Explanation: There are 8 negatives number in the matrix. Example 2: Input: grid = [[3,2],[1,0]] Output: 0 Example 3: Input: grid = [[1,-1],[-1,-1]] Output: 3 Example 4: Input: grid = [[-1]] Output: 1 Constraints: m == grid.length n == grid[i].length 1 <= m, n <= 100 -100 <= grid[i][j] <= 100 Follow up: Could you find an O(n + m) solution?