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.*;
import java.awt.geom.*;
import java.io.*;
import java.math.*;

public class Main
{

  public static void main(String[] args)
  {
    long startTime = System.nanoTime();
    int n=in.nextInt();
    int m=1;
    while(m<=1000)
    {
      if(!isPrime(n*m+1))
      {
        out.println(m);
        break;
      }
      m++;
    }
    long endTime = System.nanoTime();
    err.println("Execution Time : +" + (endTime-startTime)/1000000 + " ms");
    exit(0);
  }

  static boolean isPrime(int n)
  {
    if(n==1)
    {
      return false;
    }
    if(n==2||n==3||n==5)
    {
      return true;
    }
    for(int i=2;i<=Math.sqrt(n);i++)
    {
      if(n%i==0)
      {
        return false;
      }
    }
    return true;
  }

  static class InputReader
  {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

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

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

    static void exit(int a)
    {
      out.close();
      err.close();
      System.exit(a);
    }

    static InputStream inputStream = System.in;
    static OutputStream outputStream = System.out;
    static OutputStream errStream = System.err;
    static InputReader in = new InputReader(inputStream);
    static PrintWriter out = new PrintWriter(outputStream);
    static PrintWriter err = new PrintWriter(errStream);

}