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.StringTokenizer;
import java.io.BufferedReader;
import java.io.PrintWriter;
import java.io.InputStreamReader;
import java.util.Arrays;
public class Main {
	public static void main(String[] arhh) {
		Cin in = new Cin();
		int n = in.nextInt();
		int m = n;
		boolean[] prime = new boolean[10001];
		for(int i = 2; i < prime.length; i++) {
			prime[i] = true;
		}
		for(int i = 2; i*i < prime.length; i++) {
			if(prime[i]) {
				for(int j = i*i; j < prime.length; j+=i) {
					prime[j] = false;	
				}
			}
		}
		for(int i = 1; i <= n+10; i++) {
			int x = m*i+1;
			if(!prime[x]) {
				wr.print(i);
				break;
			}
		}
		wr.close();
	}
	

// IO -:)
	static PrintWriter wr = new PrintWriter(System.out); 
	static class Cin {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = null;
		String next() {
			while(st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(reader.readLine());
				} catch(Exception e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}
		int nextInt() { return Integer.parseInt(next());}
		long nextLong() { return Long.parseLong(next());}
	}
}