Problem: PolandBall is a young, clever Ball. He is interested in prime numbers. He has stated a following hypothesis: "There exists such a positive integer n that for each positive integer m number n·m + 1 is a prime number".

Unfortunately, PolandBall is not experienced yet and doesn't know that his hypothesis is incorrect. Could you prove it wrong? Write a program that finds a counterexample for any n.

Input

The only number in the input is n (1 ≤ n ≤ 1000) — number from the PolandBall's hypothesis. 

Output

Output such m that n·m + 1 is not a prime number. Your answer will be considered correct if you output any suitable m such that 1 ≤ m ≤ 103. It is guaranteed the the answer exists.

Examples

Input

3


Output

1

Input

4


Output

2

Note

A prime number (or a prime) is a natural number greater than 1 that has no positive divisors other than 1 and itself.

For the first sample testcase, 3·1 + 1 = 4. We can output 1.

In the second sample testcase, 4·1 + 1 = 5. We cannot output 1 because 5 is prime. However, m = 2 is okay since 4·2 + 1 = 9, which is not a prime number.

Solution (in JAVA):

Solution:
import java.util.Scanner;

public class PolandBallAndHypothesis
{
    public static void main(String [] args)
    {
        Scanner input = new Scanner(System.in);
        int n = input.nextInt(), m = 1;

        input.close();

        while(true)
        {
            int operation = n * m + 1;

            if(!isPrime(operation))
            {
                System.out.println(m);
                break;
            }

            m ++;
        }
    }

    public static boolean isPrime(int number)
    {
        if (number <= 1) 
            return false; 
         
        for (int i = 2; i < number; i++) 
            if (number % i == 0) 
                return false; 
  
        return true; 
    }
}