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.*;
import java.util.*;

public class main {
    public static void main(String[] args) throws IOException {
        sc = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(System.out);
        int n = nextInt();
        if (n == 1) {
            pw.println(3);
            pw.close();
            return;
        }
        if (n % 2 != 0) pw.println(1);
        else {
            for (int i = 2; i < 10e3; i++) {
                int ch = n * i + 1;
                int count = 0;
                for (int j = 1; j < ch; j++) {
                    if (ch % j == 0) count++;
                    if (count > 1) break;
                }
                if (count == 2) {
                    pw.println(i);
                    break;
                }
            }
        }
        pw.close();
    }
    static StringTokenizer st;
    static BufferedReader sc;
    static String next() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(sc.readLine());
        }
        return st.nextToken();
    }
    static int nextInt() throws IOException{
        return Integer.parseInt(next());
    }
    static long nextLong() throws IOException{
        return Long.parseLong(next());
    }
}