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.*;
import java.util.*;

public class Main {

    public static void main(String[] args) throws FileNotFoundException, IOException {
        BufferedReader inp = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        StringTokenizer str = new StringTokenizer(inp.readLine());
        int n = Integer.parseInt(str.nextToken());
        inp.close();
        if (n==1) {
            System.out.println(3);
            System.exit(0);
        }
        int[] a = new int[100001]; 
        for (int i=1;i<=100000;i++)
            a[i]=1;
        for (int i=2;i<=1001;i++)
            for (int j=i+i;j<=100000;j+=i){
                a[j]=0;
            }
        for (int m=1;m<=1000;m++){
            if (a[n*m+1]!=1) {
                System.out.println(m);
                System.exit(0);
            }
        }
        out.close();
    }
}