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.PrintWriter;
import java.math.BigDecimal;
import java.util.Arrays;
import java.util.Scanner;

/**
 *
 * @author Seka 14.03.95
 */
public class Seka {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        try(PrintWriter out = new PrintWriter(System.out)){
            long n = in.nextLong();
            for (long i = 1; i <= n + 10000; ++i) {
                long k = i*n + 1;
                if (isp(k)) {
                    out.println(i);
                    return;
                }
            }
        }
    }
    static boolean isp(long p) {
        for (long i = 2; i <= Math.sqrt(p); ++i) {
            if (p%i == 0) return true;
        }
        return false;
    }
}