# 0997. Find the Town Judge

https://leetcode.com/problems/find-the-town-judge

## Description

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
```

**Example 4:**

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

**Example 5:**

```
**Input:** n = 4, trust = [[1,3],[1,4],[2,3],[2,4],[4,3]]
**Output:** 3
```

**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`

## ac

```java
```
