Maximize the minimum value along a grid path

You are given an `m x n` integer matrix `A`. You start at the top-left cell `(0,0)` and want to reach the bottom-right cell `(m-1,n-1)` by moving only in 4 directions (up/down/left/right). For any path, define its **score** as the minimum value among all cells on that path. **Task**: Return the maximum possible path score. ### Input - `A`: `m x n` matrix of integers ### Output - An integer: the maximum achievable path score ### Constraints - `1 <= m, n <= 300` - `-10^9 <= A[i][j] <= 10^9` ### Example Input: ``` 5 4 5 1 2 6 7 4 6 ``` Output: ``` 4 ``` Explanation: One optimal path has minimum cell value 4, and no path can achieve a minimum > 4.