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.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Main {
	public static boolean[] isPrime;
	public static void main(String[] args) throws Throwable
	{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		populate();
		int n = Integer.parseInt(br.readLine());
		for (int i = 1; i < 1001;i++) {
			if(n*i+1<isPrime.length && !isPrime[n*i+1])
			{
				System.out.println(i);
				return;
			}
		}
	}
	
	public static void populate()
	{
		isPrime = new boolean[1<<12];
		Arrays.fill(isPrime, true);
		for (int i = 2; i < isPrime.length; i++) 
		{
			if(isPrime[i])
			{
				for(int j = i<<1;j<isPrime.length;j+=i)
				{
					isPrime[j] = false;
				}
			}
		}
	}
}