You are given an `m x n` integer grid `accounts` where `accounts[i][j]` is the amount of money the `i​​​​​​​​​​​th​​​​` customer has in the `j​​​​​​​​​​​th`​​​​ bank. Return the wealth that the richest customer has.

A customer's wealth is the amount of money they have in all their bank accounts. The richest customer is the customer that has the maximum wealth.

Example 1:

    Input: accounts = [[1,2,3],[3,2,1]]
    Output: 6
    Explanation:
    1st customer has wealth = 1 + 2 + 3 = 6
    2nd customer has wealth = 3 + 2 + 1 = 6
    Both customers are considered the richest with a wealth of 6 each, so return 6.

Example 2:

    Input: accounts = [[1,5],[7,3],[3,5]]
    Output: 10
    Explanation:
    1st customer has wealth = 6
    2nd customer has wealth = 10
    3rd customer has wealth = 8
    The 2nd customer is the richest with a wealth of 10.

Example 3:

    Input: accounts = [[2,8,7],[7,1,3],[1,9,5]]
    Output: 17

Constraints:

- `m == accounts.length`
- `n == accounts[i].length`
- `1 <= m, n <= 50`
- `1 <= accounts[i][j] <= 100`