Given an `m x n` matrix of distinct numbers, return all lucky numbers in the matrix in any order.

A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column.

Example 1:

    Input: matrix = [[3,7,8],[9,11,13],[15,16,17]]
    Output: [15]
    Explanation: 15 is the only lucky number since it is the minimum in its row and the maximum in its column.

Example 2:

    Input: matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
    Output: [12]
    Explanation: 12 is the only lucky number since it is the minimum in its row and the maximum in its column.

Example 3:

    Input: matrix = [[7,8],[1,2]]
    Output: [7]
    Explanation: 7 is the only lucky number since it is the minimum in its row and the maximum in its column.

Constraints:

- `m == mat.length`
- `n == mat[i].length`
- `1 <= n, m <= 50`
- `1 <= matrix[i][j] <= 105`.
- All elements in the matrix are distinct.