Problem:
Score: 100 points

Problem Statement

Takahashi is solving quizzes. He has easily solved all but the last one.

The last quiz has three choices: 1, 2, and 3.

With his supernatural power, Takahashi has found out that the choices A and B are both wrong.

Print the correct choice for this problem.

Constraints

Each of the numbers A and B is 1, 2, or 3.

A and B are different.

Input

Input is given from Standard Input in the following format:

A
B

Output

Print the correct choice.

Sample Input 1

3
1

Sample Output 1

2

When we know 3 and 1 are both wrong, the correct choice is 2.

Sample Input 2

1
2

Sample Output 2

3

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        int N = int.Parse(Console.ReadLine());
        List<int> a = Console.ReadLine().Split(' ').Select(o => int.Parse(o)).ToList();

        for (int i = 1; i <= N; i++)
        {
            if (!a.Any(o => o == i))
            {
                if(i == 1)
                    Console.WriteLine(-1);
                else
                Console.WriteLine(N + 1 - i);
                break;
            }
            int b = a.TakeWhile(o => o != i).ToArray().Count();
            a.RemoveRange(0, b);
        }
    }
}