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.io.*;
import java.util.*;
public class Main{
    public static void main(String []args){
        Scanner in = new Scanner(System.in);
        solution solve = new solution();
        int test = 1;
        while(test-->0)
            solve.ans();
    }
    public static class solution{
        void ans()
        {
            Scanner in = new Scanner(System.in);
            int n = in.nextInt();
            boolean cond = false;
            for(int i=1;i<110000;i++){
                if(isPrime(1+(n*i)) == false) {
                    System.out.println(i);
                    cond = true;
                    break;
                }
            }
            if(cond == false)
                System.out.println(-1);
        }

        private boolean isPrime(int n){
            int count = 0;
            for(int i=1;i<=Math.sqrt(n);i++){
                if(n%i == 0)
                    count++;
            }
            if(count>1)
                return false;
            else
                return true;
        }
    }
}