# 997. Find the Town Judge

# In a town, there are N people labelled from 1 to N.  There is a rumor that one of these people is secretly the town judge.
# If the town judge exists, then:
# The town judge trusts nobody.
# Everybody(except for the town judge) trusts the town judge.
# There is exactly one person that satisfies properties 1 and 2.
# You are given trust, an array of pairs trust[i] = [a, b] representing that the person labelled a trusts the person labelled b.
# If the town judge exists and can be identified, return the label of the town judge.  Otherwise, return -1.

# 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


class Solution(object):
    def findJudge(self, N, trust):
        status = [0] * N

        for a, b in trust:
            status[a - 1] -= 1
            status[b - 1] += 1

        for i in range(len(status)):
            if status[i] == N - 1:
                return i + 1

        return -1
