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 Solution {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Set<Integer> primes = new TreeSet<>(primes(3000));
        for(int i = 1; ; i++) {
            int o = i * n + 1;
            if (!primes.contains(o)) {
                System.out.println(i);
                return;
            }
        }
    }

    public static List<Integer> primes(int n) {
        List<Integer> primes = new ArrayList<>();
        int[] largestPrime = new int[n + 1];
        for (int i = 2; i <= n; i++) {
            if (largestPrime[i] != 0) continue;
            primes.add(i);
            for (int j = 2 * i; j <= n; j += i) largestPrime[j] = i;
        }
        return primes;
    }
}