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.BufferedReader;
import java.io.FileReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class Main {
    static int n;

    static boolean isPrime(int a) {
        for (int i = 2; i * i <= a; i++)
            if (a % i == 0)
                return false;
        return true;
    }

    public static void main(String args[]) throws Exception {
        init();
        n = nextInt();
        for (int i = 1; i < 1e3 + 500; i++) {
            if (!isPrime(n * i + 1)){
                out.println(i);
                out.close();
                return;
            }
        }
        out.close();
    }

    static BufferedReader scan;
    static PrintWriter out;
    static StringTokenizer st;

    static void init() {
        scan = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
    }

    static void init(String name1, String name2) throws Exception {
        try {
            scan = new BufferedReader(new FileReader(name1));
            out = new PrintWriter(name2);
        } catch (Exception e) {
            scan = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        }
    }

    static String next() throws Exception {
        while (st == null || !st.hasMoreTokens())
            st = new StringTokenizer(scan.readLine());
        return st.nextToken();
    }

    static int nextInt() throws Exception {
        return Integer.parseInt(next());
    }

    static long nextLong() throws Exception {
        return Long.parseLong(next());
    }
}

class Segment {
    int value;
    StringBuilder history;

}