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:
//package Codeforces;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;

public class PolandBallAndHypothesis {
	static boolean [] prime = new boolean[(int)1e6+10];
	public static void generate(){
		Arrays.fill(prime, true);
		for (int i = 2; i < (int)1e3; i++) {
			if(!prime[i])
				continue;
			for (int j = i*i; j < prime.length; j+=i) {
				prime[j]=false;
			}
		}
	}
	
public static void main(String[] args) {
	Scanner sc =new Scanner(System.in);
	int x = sc.nextInt();
	generate();
	if(x%2==1)
		System.out.println(3);
	else{
		for (int i = 1; i <=(int)1e3; i++) {
			int tmp = x*i +1;
			if(prime[tmp])
				continue;
			else{
				System.out.println(i);
				break;
			}
		}
	}

}
}