A company is planning to interview `2n` people. Given the array `costs` where `costs[i] = [aCosti, bCosti]`, the cost of flying the `ith` person to city `a` is `aCosti`, and the cost of flying the `ith` person to city `b` is `bCosti`.

Return the minimum cost to fly every person to a city such that exactly `n` people arrive in each city.

Example 1:

    Input: costs = [[10,20],[30,200],[400,50],[30,20]]
    Output: 110
    Explanation:
    The first person goes to city A for a cost of 10.
    The second person goes to city A for a cost of 30.
    The third person goes to city B for a cost of 50.
    The fourth person goes to city B for a cost of 20.

    The total minimum cost is 10 + 30 + 50 + 20 = 110 to have half the people interviewing in each city.

Example 2:

    Input: costs = [[259,770],[448,54],[926,667],[184,139],[840,118],[577,469]]
    Output: 1859

Example 3:

    Input: costs = [[515,563],[451,713],[537,709],[343,819],[855,779],[457,60],[650,359],[631,42]]
    Output: 3086

Constraints:

- `2 * n == costs.length`
- `2 <= costs.length <= 100`
- `costs.length` is even.
- `1 <= aCosti, bCosti <= 1000`