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.util.*;

public class Main {
	private static final int MAX = 1000001;
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		boolean[] primes = sieve(MAX);
		
		int n = sc.nextInt();
		int m = 1;
		while(true) {
			if (primes[(n*m) + 1] == false) {
				System.out.println(m);
				return;
			}
			++m;
		}
	}
	
	public static boolean[] sieve(int range) {
		boolean[] primes = new boolean[range+1];
		
		Arrays.fill(primes, true);
		
		primes[1] = false;
		
		int sqrtRange = (int) Math.sqrt(range);
		for(int factor=2; factor<=sqrtRange; factor++) {
			if(primes[factor] == true) {
				int div = range/factor;
				
				for(int i=factor; i <= div; i++) {
					primes[factor*i] = false;
				}
			}
		}
		
		return primes;
	}
}