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.io.*;

public class CF755A{ 
  public static boolean [] isPrime;
  public static void main(String[] args)throws Exception {
    InputReader in = new InputReader(System.in);
    PrintWriter pw = new PrintWriter(new OutputStreamWriter(System.out));
    
    isPrime = new boolean[(int)1e6+500];
    sieve((int)1e6+50);
    
    
    int n = in.nextInt();
    
    for(int i = 1; i <= 1000; i++){
      if(!isPrime[n*i + 1]){
        pw.println(i);
        break;
      }
    }
    
    
    pw.close();
  }
  
  static void sieve(int n){
     //boolean[] isPrime = new boolean[n+1];
     Arrays.fill(isPrime, true); 
     isPrime[0] = isPrime[1] = false;
     for (int factor = 2; factor*factor <= n; factor++) {
       if (isPrime[factor]) {
         for (int j = factor; factor*j <= n; j++) {
           isPrime[factor*j] = false;
         }
       }
     }
  }
  
  static class InputReader {
    public BufferedReader reader;
    public StringTokenizer tokenizer;
    
    public InputReader(InputStream stream) {
      reader = new BufferedReader(new InputStreamReader(stream));
      tokenizer = null;
    }
    
    public String next()throws Exception {
      while (tokenizer == null || !tokenizer.hasMoreTokens())
        tokenizer = new StringTokenizer(reader.readLine());
      return tokenizer.nextToken();
    }
    
    public String nextLine()throws Exception {
      String line = null;
      tokenizer = null;
      line =  reader.readLine();
      return line;
    }
    
    public int nextInt()throws Exception {
      return Integer.parseInt(next());
    }
    
    public double nextDouble() throws Exception{
      return Double.parseDouble(next());
    }
    
    public long nextLong()throws Exception {
      return Long.parseLong(next());
    }
    
  }
}