On a N * N grid, we place some 1 * 1 * 1 cubes.
Each value v = grid[i][j] represents a tower of v cubes placed on top of grid cell (i, j).
Return the total surface area of the resulting shapes.
Example 1:
Input: [[2]] Output: 10
Example 2:
Input: [[1,2],[3,4]] Output: 34
Example 3:
Input: [[1,0],[0,2]] Output: 16
Example 4:
Input: [[1,1,1],[1,0,1],[1,1,1]] Output: 32
Example 5:
Input: [[2,2,2],[2,1,2],[2,2,2]] Output: 46
Note:
1 <= N <= 500 <= grid[i][j] <= 50