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.*;
public class p2{
  static boolean[] pr=new boolean[100005];
  public static void main(String[] args) {
    Scanner in=new Scanner(System.in);

    int n=in.nextInt();
    pre();
    //for(int i=0;i<100;i++){System.out.println(i+" "+pr[i]);}
    for(int i=1;i<1000;i++){
      int p=n*i+1;
      if(!pr[p]){System.out.println(i);break;}
    }

  }
  public static void pre()    //to find all prime numbers...
  {
  	for(int i=2; i<100005; i++)
  		pr[i] = true;
  	pr[0] = pr[1] = false;

  	for(int i=2; i<100005; i++)
  			for(int j=2*i; j<100005; j+=i)
  				pr[j] = false;
  }
}