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.*;
import java.io.*;
import java.math.*;
import static java.lang.Math.*;

public class A implements Runnable {

  public static void main(String[] args) {
    new Thread(null, new A(), "", 1 << 28).start();
  }

  public void run() {
    Scanner sc = new Scanner();
    int n = sc.nextInt();

    boolean[] prime = sieve(1000010);

    for (int i = 1; i < 10; i++) {
      if (!prime[n * i + 1]) {
        System.out.println(i);
        return;
      }
    }
  }

  static boolean[] sieve(int N) {
    boolean[] a = new boolean[N + 1];
    Arrays.fill(a, true);
    a[0] = a[1] = false;
    for (int p = 2; p * p <= N; p++)
      if (a[p]) {
        // Iterate through all multiples m of the prime and mark
        // them as not prime.
        for (int m = p * p; m <= N; m += p)
          a[m] = false;
      }
    return a;
  }

  class Scanner {
    BufferedReader r;
    StringTokenizer t;

    Scanner() {
      r = new BufferedReader(new InputStreamReader(System.in), 1 << 15);
      t = null;
    }

    String next() {
      while (t == null || !t.hasMoreTokens()) {
        try {
          t = new StringTokenizer(r.readLine());
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
      return t.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(next());
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    long nextLong() {
      return Long.parseLong(next());
    }

    BigInteger nextBigInteger() {
      return new BigInteger(next());
    }
  }
}