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.*;

public class test21
{
    public static void main(String args[])
    {
        Scanner in =new Scanner(System.in);
        test21 b=new test21();
        int n=in.nextInt();
        int m=1;
        int ans=1;
        while(ans!=0)
        {
            m++;
            ans=b.isprime((n*m+1));
            
        }
        System.out.println(m);
    }
    public int isprime(int n)
        {
            int i;
			if((n%2)==0)
			return 0;
            for(i=3;i<=(int)(Math.sqrt(n));i+=2 )
        	{
            if((n%i)==0)
            return 0;
            }
			return 1;
			}
}