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.*;
import java.math.*;
 
public class VentureCup17Q1
{
    public static void main(String[] args) throws IOException
    {
        FastScanner obj = new FastScanner();
        out = new PrintWriter(new BufferedOutputStream(System.out));
      	int n = obj.nextInt();
      	for(int i=1;i<=1000;i++)
      		if(isPrime((n*i)+1))
      		{
      			out.println(i);
      			break;
      		}
      	
        out.close();
   }
   public static boolean isPrime(int n)
   {
		for(int i=2;i<n;i++)
   		{
   			if(n%i==0)
   				return true;
		}
	   	return false;
   }
   

   //-----------PrintWriter for faster output---------------------------------
   public static PrintWriter out;
      
   //-----------FastScanner class for faster input----------
   public static class FastScanner {
        BufferedReader br;
        StringTokenizer tokenizer;
 
        public FastScanner() throws IOException {
            br = new BufferedReader(new InputStreamReader(System.in));
            tokenizer = new StringTokenizer(br.readLine().trim());
        }
 
        String next() {
            while (tokenizer == null || !tokenizer.hasMoreElements()) {
                try {
                    tokenizer = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                    }
            }
          return tokenizer.nextToken();
        }
 
        int nextInt() {
            return Integer.parseInt(next());
        }
 
        long nextLong() {
            return Long.parseLong(next());
        }
 
        double nextDouble() {
            return Double.parseDouble(next());
        }
      
        int[] nextIntArray() throws IOException {
            String[] line = br.readLine().trim().split(" ");
            int[] out = new int[line.length];
            
            for (int i = 0; i < line.length; i++) {
                out[i] = Integer.valueOf(line[i]);
            }
            return out;
        }
        
        BigInteger nextBigInteger() throws IOException {
            return new BigInteger(next());
        }
        
        String nextLine(){
            String str = "";
	        try {
	            str = br.readLine();
	        } catch (IOException e) {
	            e.printStackTrace();
	        }
	        return str;
        }

   }
   //--------------------------------------------------------
}