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.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class testPolandHypothesis
{
	public testPolandHypothesis()
	{
		
	}
	
	public class FastScanner 
    {
        public BufferedReader br;
        public StringTokenizer st;

        public FastScanner(String fileName)
        {
            try 
            {
                br = new BufferedReader(new FileReader(fileName));
            } 
            catch (FileNotFoundException e)
            {
            	
            }
        }

        public FastScanner() 
        {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

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

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

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

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

	public class polandBallHypothesis 
	{
		public polandBallHypothesis()
		{
			
		}
		
		public void InitVariables()
		{
			
		}
		
		public int GetM(int _number,int _flag)
		{
			int m = 0;
			int flag = _flag;
			int resultantFormula = _number*flag+1;
			
			if(IsPrimeNumber(resultantFormula))
			{
				flag = flag+1;
				m = GetM(_number,flag);
			}
			else
			{
				m = flag;
			}
			
			return m;
		}
		
		public Boolean IsPrimeNumber(int _number)
		{
			Boolean found = true;
			
			for(int i = 2 ; i < _number; i++)
			{
				if(_number % i == 0)
					found = false;
			}
			
			return found;
		}
	}

	public FastScanner in;
	public PrintWriter out;
	public polandBallHypothesis pbh;
	
	public void Solve()
	{
		in = new FastScanner();
		out = new PrintWriter(System.out);
		pbh = new polandBallHypothesis();
		
		int number = in.nextInt();
		out.println(pbh.GetM(number, 1));
		
		out.close();
	}
	
	public static void main(String[] args)
	{
		new testPolandHypothesis().Solve();
	}
}