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.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class test {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        boolean ar[] = sieve(n*1000);
        for(int i=1;i<=1000;i++){
        	if(!(ar[n*i+1])){
        		System.out.println(i);
        		break;
        	}
        }
        
    }
    
    public static boolean[] sieve(int n)
	{
	   boolean[] prime=new boolean[n+1];
	   Arrays.fill(prime,true);
	   prime[0]=false;
	   prime[1]=false;
	   double m = Math.sqrt(n);
	   for (int i=2; i<=m; i++)
	      if (prime[i])
	         for (int k=i*i; k<=n; k+=i)
	            prime[k]=false;

	   return prime;
	} 
}