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.Scanner;

public class VC8PolandBall {
	public static void main(String[] args) {
		Scanner kboard = new Scanner(System.in);
		int n = Integer.parseInt(kboard.nextLine());
		if (n == 1) {
			System.out.println(3);
			System.exit(0);
		}
		if (n % 2 != 0) {
			System.out.println("1");
 		} else {
 			int current = 1;
 			while (isPrime(current * n + 1) == true) {
 				current++;
 			}
 			System.out.println(current);
 		}
	}
	public static boolean isPrime(int x) {
		for (int i = 2; i <= Math.sqrt(x); i++) {
			if (x % i == 0) {
				return false;
			}
		}
		return true;
	}
}