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.Scanner;
import java.math.BigInteger;
import java.util.Arrays;
import java.lang.*;
import java.io.*;
import java.util.*;
/*Created By Prakhar Bindal, Indian institute of technology,Kharagpur*/
/*Build using Java 8.0 Chelper plugin for ubuntu 16.04*/
public class test
{
	public static boolean checkprime(int n)
	{
		if(n==1)
        return false;
    if(n==2||n==3)
        return true;
    int i;
    for(i=2;i*i<=n;i++)
    {
        if(n%i==0)
            break;
    }
    if(i*i>n)
        return true;
    else
        return false;
	}
	public static int gcd(int a,int b)
	{
		if(a==0)
			return b;
		return gcd(b%a,a);
	}
	public static boolean check(int a,int b,int c)
	{
		int i=0;
		while(i*a<=c)
		{
			if((c-i*a)%b==0)
				return true;
			i++;
		}
		return false;
	}
	public static boolean sum(int a[],int n)
	{
	    Arrays.sort(a);	
	    int i;
	 	for(i=0;i<n-1;i++)
		{
             if(a[i+1]>=a[i]+1)
             	break;
		}
		if(i==n-1)
			return true;
		else
			return false;
	}
	public static void main(String[] args)
	{
	  		Scanner in = new Scanner(System.in);
            int n=in.nextInt();
            for(int m=1;m<=1000;++m)
            {
            	if(!checkprime(n*m+1))
            	{
            		System.out.print(m);
            		break;
            	}
            }
           
    }
}