You are given an integer `n` indicating there are `n` people numbered from `0` to `n - 1`. You are also given a 0-indexed 2D integer array `meetings` where `meetings[i] = [xi, yi, timei]` indicates that person `xi` and person `yi` have a meeting at `timei`. A person may attend multiple meetings at the same time. Finally, you are given an integer `firstPerson`.

Person `0` has a secret and initially shares the secret with a person `firstPerson` at time `0`. This secret is then shared every time a meeting takes place with a person that has the secret. More formally, for every meeting, if a person `xi` has the secret at `timei`, then they will share the secret with person `yi`, and vice versa.

The secrets are shared instantaneously. That is, a person may receive the secret and share it with people in other meetings within the same time frame.

Return a list of all the people that have the secret after all the meetings have taken place. You may return the answer in any order.

Example 1:

    Input: n = 6, meetings = [[1,2,5],[2,3,8],[1,5,10]], firstPerson = 1
    Output: [0,1,2,3,5]
    Explanation:
    At time 0, person 0 shares the secret with person 1.
    At time 5, person 1 shares the secret with person 2.
    At time 8, person 2 shares the secret with person 3.
    At time 10, person 1 shares the secret with person 5.​​​​
    Thus, people 0, 1, 2, 3, and 5 know the secret after all the meetings.

Example 2:

    Input: n = 4, meetings = [[3,1,3],[1,2,2],[0,3,3]], firstPerson = 3
    Output: [0,1,3]
    Explanation:
    At time 0, person 0 shares the secret with person 3.
    At time 2, neither person 1 nor person 2 know the secret.
    At time 3, person 3 shares the secret with person 0 and person 1.
    Thus, people 0, 1, and 3 know the secret after all the meetings.

Example 3:

    Input: n = 5, meetings = [[3,4,2],[1,2,1],[2,3,1]], firstPerson = 1
    Output: [0,1,2,3,4]
    Explanation:
    At time 0, person 0 shares the secret with person 1.
    At time 1, person 1 shares the secret with person 2, and person 2 shares the secret with person 3.
    Note that person 2 can share the secret at the same time as receiving it.
    At time 2, person 3 shares the secret with person 4.
    Thus, people 0, 1, 2, 3, and 4 know the secret after all the meetings.

Constraints:

- `2 <= n <= 105`
- `1 <= meetings.length <= 105`
- `meetings[i].length == 3`
- `0 <= xi, yi <= n - 1`
- `xi != yi`
- `1 <= timei <= 105`
- `1 <= firstPerson <= n - 1`