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.StringTokenizer;

public class Solution {

    public static void main(String[] args) {
        MyScanner scanner = new MyScanner();
        out = new PrintWriter(new BufferedOutputStream(System.out));

        // Start writing your solution here. -------------------------------------
        solve(scanner, out);

        // Stop writing your solution here. -------------------------------------
        out.close();
    }

    static boolean isPrime(int n) {
        if (n <= 1)
            return false;
        else if (n <= 3)
            return true;
        else if (n % 2 == 0 || n % 3 == 0)
            return false;
        int i = 5;
        while (i * i <= n) {
            if ((n % i) == 0 || (n % (i + 2) == 0)) {
                return false;
            } else {
                i = i + 6;
            }
        }

        return true;
    }

    private static void solve(MyScanner scanner, PrintWriter out) {
        int n = scanner.nextInt();
        if (n % 2 == 1) {
            System.out.println(3);
        } else {
            int m = 1;
            while (true) {
                int temp = m * n + 1;
                if(!isPrime(temp)){
                    System.out.println(m);
                    break;
                }
                m++;
            }
        }


    }


    //-----------PrintWriter for faster output---------------------------------
    public static PrintWriter out;

    //-----------MyScanner class for faster input----------
    public static class MyScanner {
        BufferedReader br;
        StringTokenizer st;

        public MyScanner() {
//            try {
            br = new BufferedReader(new InputStreamReader(System.in));
//            } catch (FileNotFoundException e) {
//                e.printStackTrace();
//            }
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

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

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

    }

}