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.HashSet;
import java.util.Scanner;

public class Main {
static HashSet<Integer> primes  = new HashSet<>();
    public static void main(String[] args) {
	// write your code here
        Stieve();
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        boolean stop = false;
       int m = 1;
        //start at m
        //keep going until you reach point where the sum is not a prime
        while (primes.contains((n*m)+1))
            m++;
        System.out.println(m);
    }

    private static void Stieve() {
        int size = 1000000;
        boolean[] visited = new boolean[size];
        for (long i=2;i<size;i++) {
            if (!visited[(int)i]) {
               primes.add((int)i);
                for (long j = i * i; j < size; j+=i) {
                   // System.out.println(j);
                    visited[(int) j] = true;
                }
            }
        }
    }
}