using System;

using System.Linq;

public class Program

{

    /*

    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) Everyone trusts the town judge (except for the town judge, who cannot trust anyone).

    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.

    */

    public static int FindJudge(int numPeople, int[][] trust) {

        return -1;

    }

    public static void Main()

    {

        var test1 = FindJudge(2, new int[][] {

            new int[] {1, 2}

        });

​

        Console.WriteLine($"{test1} should be 2");

​

        var test2 = FindJudge(3, new int[][] {

            new int[] {1, 3},

            new int[] {2, 3}

        });

​

        Console.WriteLine($"{test2} should be 3");

​

        var test3 = FindJudge(3, new int[][] {

            new int[] {1, 3},

            new int[] {2, 3},

            new int[] {3, 1}});

​

        Console.WriteLine($"{test3} should be -1");

​

        var test4 = FindJudge(3, new int[][] {

            new int[] {1, 2},

            new int[] {2, 3}});

​

        Console.WriteLine($"{test4} should be -1");

​

        var test5 = FindJudge(4, new int[][] {

            new int[] {1, 3},

            new int[] {1, 4},

            new int[] {2, 3},

            new int[] {2, 4},

            new int[] {4, 3}});

​

        Console.WriteLine($"{test5} should be 3");

        var test6 = FindJudge(4, new int[][] {

            new int[] {1, 4},

            new int[] {1, 3},

            new int[] {2, 3},

            new int[] {4, 3},

            new int[] {2, 4}});

​

        Console.WriteLine($"{test6} should be 3");

    }

}