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.*;
import java.io.*;
import java.math.*;
import static java.lang.Math.*;


public class Main {
	private final Scanner scan = new Scanner(System.in);
	private final PrintStream out = new PrintStream(System.out);
    int n;
	
	public static void main (String[] arg) throws IOException {new Main().run();}
	
	
	void run () throws IOException {
	    n = scan.nextInt();
	    
	    for (int i = 1; i <= 1000; i++) {
	    	if (!isPrime(n * i + 1)) {out.println(i); return;}
	    }
	}
	
	
	boolean isPrime (int a) {
		if (a == 2 || a == 3) return true;
		if (a % 2 == 0 || a % 3 == 0 || a == 1) return false;
		
		for (int i = 3; i * i <= a; i+=2) {
			if (a % i == 0) return false;
		}
		return true;
	}
}