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.Arrays;

public class A {

	public static boolean[] isPrime(int N) {
		boolean[] prime = new boolean[N + 1];
		Arrays.fill(prime, true);

		prime[0] = false;
		prime[1] = false;

		for (int i = 2; i * i <= N; i++) {

			if (prime[i] == true) {

				for (int j = i * i; j <= N; j += i) {

					prime[j] = false;

				}
			}

		}

		return prime;

	}

	
	public static void main(String[] args) {
		
		

		BufferedReader rd=new BufferedReader(new InputStreamReader(System.in));
		boolean[] isPrime=isPrime(1000000);
		try{
			
			int n=Integer.parseInt(rd.readLine());
			
			
			int m=1;
			int c=0;
			for(int i=1;i<1000000;i++){
			
				int ans=n*m+1;
				if(isPrime[ans]==false){
					c=i;
					break;
				}
				m++;
			}
			
			System.out.println(c);
			
		}catch(Exception e){
			e.printStackTrace();
		}
	}

}