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.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
		int n = 1000000;
		boolean prime[] = new boolean[n+1]; 
		for(int i=0;i<n;i++) 
			prime[i] = true; 
		for(int p = 2; p*p <=n; p++)
			if(prime[p] == true) 
				for(int i = p*p; i <= n; i += p) 
					prime[i] = false;
		//		for (int i = 0; i < prime.length; i++) {
		//
		//		}
		int number = Integer.parseInt(bf.readLine());
		if(number ==1)System.out.println(3);
		else if(number %2 == 1)System.out.println(1);
		else {
			ArrayList<Integer> oddNoPrime = new ArrayList<>();
			for (int i = 2; i < prime.length; i++)
				if(!prime[i]/*&&i%2==0*/)oddNoPrime.add(i);
			for (int i = 1; i < 1001; i++) 
				if(oddNoPrime.contains((number*i)+1)){
					System.out.println(i);
					break;
				}

		}
	}
}