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.StringTokenizer;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.io.IOException;
public class bfs_dfs {

	public static void main(String[] args)
	{
		scanner in = new scanner();
		int n = in.nextInt();
	  if(n==1)
		  System.out.println(3);
	  else
	  {
		  if(n%2==0)
		  {
			 int k = 1;
			 while(new BigInteger(String.valueOf(n*k+1)).isProbablePrime(1))
			 {
				 k++;
			 }
			 System.out.println(k);
		  }
		  else
			  System.out.println(1);
	  }
	}
}
class scanner
{
	 BufferedReader br;
	 StringTokenizer st;
	
	public scanner()
	{
		br = new BufferedReader(new InputStreamReader(System.in));
		st = null;
	}
	public String next()
	{
		while(st==null || !st.hasMoreElements())
		{
			try
			{
				st = new StringTokenizer(br.readLine());
			}
			catch(IOException e){
				e.printStackTrace();
			}
		}
		return st.nextToken();
	}
	public int nextInt()
	{
		return Integer.parseInt(next());
	}}