Given an n x n grid containing only values 0 and 1, where 0 represents water and 1 represents land, find a water cell such that its distance to the nearest land cell is maximized, and return the distance.
If no land or water exists in the grid, return -1.
The distance used in this problem is the Manhattan distance: the distance between two cells (x0, y0) and (x1, y1) is |x0 - x1| + |y0 - y1|.
n == grid.lengthn == grid[i].length1 <= n <= 100grid[i][j] is 0 or 1grid = [[1,0,1],[0,0,0],[1,0,1]]2grid = [[1,0,0],[0,0,0],[0,0,0]]4