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.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;

public class A {
  int[] primes = getPrimes((int) 1e6);
  int solve(int n) {
    for (int i = 1; ; i++) {
      int x = i * n + 1;
      if (Arrays.binarySearch(primes, x) < 0) return i;
    }
  }

  private void solve(Scanner in, PrintWriter out) {

    int N = in.nextInt();
    out.println(solve(N));
  }
  public static int[] getPrimes(int N) {
    ArrayList<Integer> primes = new ArrayList<>();
    boolean[] isComposite = new boolean[N + 1];
    primes.add(2);
    for (int i = 3; i <= N; i += 2)
      if (!isComposite[i]) {
        primes.add(i);
        for (int j = i * 2; j <= N; j += i) {
          isComposite[j] = true;
        }
      }
    int[] array = new int[primes.size()];
    for (int i = 0; i < primes.size(); i++) {
      array[i] = primes.get(i);
    }
    return array;
  }

  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    PrintWriter out = new PrintWriter(System.out);
    new A().solve(in, out);
    in.close();
    out.close();
  }
}