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.math.BigInteger;
import java.util.*;

public class Program {
    
    private static PrintWriter out;
    
    private static <T> void mprintln(T ... ar){
        for(T i: ar) out.print(i + " ");
        out.println();
    }
    
    public static void main(String[] args) throws FileNotFoundException{

        // Input from file
        // File inputFile = new File("JavaFile.txt");
        // File outputFile = new File("JavaOutputFile.txt");
        // FileReader fileReader = new FileReader(inputFile);
        // Here it ends

        MyScanner sc = new MyScanner();
        // MyScanner sc = new MyScanner(fileReader);

        out = new PrintWriter(new BufferedOutputStream(System.out)); // Output to console
        // out = new PrintWriter(new PrintStream(outputFile)); // Output to file

        getAns(sc);

        out.close();
    }
    
    private static void getAns(MyScanner sc){
        int n = sc.ni();
        
        if(n % 2 == 1){
            out.println(3);
            return;
        }
        
        for(int i = 1; i <= 1000; i++) if(OK(i, n)){
            out.println(i);
            break;
        }
    }
    
    private static boolean OK(int m, int n){
        return !isPrime(n * m + 1);
    }

    private static boolean isPrime(int n) {
        int i = 2;
        while(i * i <= n){
            if(n % i == 0) return false;
            ++i;
        }
        return true;
    }
    
    static class MyScanner{
        BufferedReader br;
	StringTokenizer st;

	MyScanner(FileReader fileReader){
            br = new BufferedReader(fileReader);
	}

	MyScanner(){
            br = new BufferedReader(new InputStreamReader(System.in));
	}

	String nn(){
            while(st == null || !st.hasMoreElements()){
		try{
                    st = new StringTokenizer(br.readLine());
		}catch(IOException e){
                    e.printStackTrace();
		}
            }
            return st.nextToken();
	}
        
        String nextLine(){
            String ans = "";
            try {
                ans = br.readLine();
            } catch (IOException ex) {
                ex.printStackTrace();
            }
            return ans;
        }

	char nc(){
            return nn().charAt(0);
	}

	int ni(){
            return Integer.parseInt(nn());
	}

	long nl(){
            return Long.parseLong(nn());
	}

	double nd(){
            return Double.parseDouble(nn());
	}

	int[] niArr0(int n){
            int[] ar = new int[n];
            for(int i = 0; i < n; i++) ar[i] = ni();
            return ar;
	}

        int[] niArr1(int n){
            int[] ar = new int[n + 1];
            for(int i = 1; i <= n; i++) ar[i] = ni();
            return ar;
	}

        long[] nlArr0(int n){
            long[] ar = new long[n];
            for(int i = 0; i < n; i++) ar[i] = nl();
            return ar;
        }

        long[] nlArr1(int n){
            long[] ar = new long[n + 1];
            for(int i = 1; i <= n; i++) ar[i] = nl();
            return ar;
        }
    }
}