Please solve the programming task below using a self-contained code snippet in a markdown code block.

You are given an m x n grid where each cell can have one of three values:

0 representing an empty cell,
1 representing a fresh orange, or
2 representing a rotten orange.

Every minute, any fresh orange that is 4-directionally adjacent to a rotten orange becomes rotten.
Return the minimum number of minutes that must elapse until no cell has a fresh orange. If this is impossible, return -1.
 
Please complete the following python code precisely:
```python
class Solution:
    def orangesRotting(self, grid: List[List[int]]) -> int:
```