In a town, there are `n` people labeled from `1` to `n`. There is a rumor that one of these people is secretly the town judge.

If the town judge exists, then:

1. The town judge trusts nobody.
2. Everybody (except for the town judge) trusts the town judge.
3. There is exactly one person that satisfies properties 1 and 2.

You are given an array `trust` where `trust[i] = [ai, bi]` representing that the person labeled `ai` trusts the person labeled `bi`.

Return the label of the town judge if the town judge exists and can be identified, or return `-1` otherwise.

Example 1:

    Input: n = 2, trust = [[1,2]]
    Output: 2

Example 2:

    Input: n = 3, trust = [[1,3],[2,3]]
    Output: 3

Example 3:

    Input: n = 3, trust = [[1,3],[2,3],[3,1]]
    Output: -1

Constraints:

- `1 <= n <= 1000`
- `0 <= trust.length <= 104`
- `trust[i].length == 2`
- All the pairs of `trust` are unique.
- `ai != bi`
- `1 <= ai, bi <= n`