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 codeChef;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class PollandBallHypothesis {

	public static boolean isPrime (int n) {
		
		if (n ==1)
			return false;
		
		for(int i=2; i*i<=n; i++) {
			if(n%i==0)
				return false;
		}
		
		return true;
	}
	
	public static void main(String[] args) throws Exception {
		// TODO Auto-generated method stub
		BufferedReader br  = new BufferedReader(new InputStreamReader(System.in));
		int number = Integer.parseInt(br.readLine());
		
		int m=1;
		
		while(true) {
			int n = m*number + 1;
			
			if(!isPrime(n)) {
				break;
			}
			
			m++;
		}
		
		System.out.println(m);
		
	}
}