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 A 
{
	public static boolean[] isPrime;
	public static void main(String[] args) throws IOException
	{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
		int n = Integer.parseInt(br.readLine());
		sieve(1000002);
		for(int m = 1; m <= 1000; m++)
			if(!isPrime[n*m + 1])
			{
				pw.println(m);
				br.close();
				pw.close();
				System.exit(0);
			}
	}
	public static void sieve(int upper)
	{
		upper++;
		isPrime = new boolean[upper];
		Arrays.fill(isPrime, true);
		isPrime[0] = isPrime[1] = false;
		for(long i = 2; i < upper; i++)
			if(isPrime[(int)i])
				for(long j = i*i; j < upper; j += i)
					isPrime[(int)j] = false;
	}  
}