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

Runtime:?3 ms, faster than?91.59%?of?Java?online submissions for?Find the Town Judge.

Memory Usage:?71.5 MB, less than?72.24%?of?Java?online submissions for?Find the Town Judge.

法官不信任任何人，所有其他人信任法官；