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:
/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
public class Tester
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner s = new Scanner(System.in);
		
		int N=1000000;
		boolean isPrime[] = new boolean[N+1];
		
		Arrays.fill(isPrime, true);
		
		isPrime[0]=false;
		isPrime[1]=false;
		
		for(int i=2; i<=Math.sqrt(N); i++)
		{
			if(isPrime[i])
			{
				for(int j=i*i; j<=N; j=j+i)
				{
					isPrime[j]=false;
				}
			}
		}
		
		
		int n=s.nextInt();
		
		for(int m=1; m<=1000; m++)
		{
			if(isPrime[n*m+1] == false)
			{
				System.out.println(m);
				return;
			}
		}
		
		
	}
}