There is an `m x n` matrix that is initialized to all `0`'s. There is also a 2D array `indices` where each `indices[i] = [ri, ci]` represents a 0-indexed location to perform some increment operations on the matrix.

For each location `indices[i]`, do both of the following:

1. Increment all the cells on row `ri`.
2. Increment all the cells on column `ci`.

Given `m`, `n`, and `indices`, return the number of odd-valued cells in the matrix after applying the increment to all locations in `indices`.

Example 1:

    Input: m = 2, n = 3, indices = [[0,1],[1,1]]
    Output: 6
    Explanation: Initial matrix = [[0,0,0],[0,0,0]].
    After applying first increment it becomes [[1,2,1],[0,1,0]].
    The final matrix is [[1,3,1],[1,3,1]], which contains 6 odd numbers.

Example 2:

    Input: m = 2, n = 2, indices = [[1,1],[0,0]]
    Output: 0
    Explanation: Final matrix = [[2,2],[2,2]]. There are no odd numbers in the final matrix.

Constraints:

- `1 <= m, n <= 50`
- `1 <= indices.length <= 100`
- `0 <= ri < m`
- `0 <= ci < n`

Follow up: Could you solve this in `O(n + m + indices.length)` time with only `O(n + m)` extra space?