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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.TreeSet;
import java.util.ArrayList;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author _disturbed_
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastScanner in = new FastScanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        APolandBallAndHypothesis solver = new APolandBallAndHypothesis();
        solver.solve(1, in, out);
        out.close();
    }

    static class APolandBallAndHypothesis {
        public void solve(int tt, FastScanner fs, PrintWriter out) {
            int n = fs.nextInt();
            ArrayList<Integer> primes = new ArrayList<>();
            int N = (int) 1e6 + 10;
            boolean[] sieve = new boolean[N];
            Primes.generateSieve(sieve);
            Primes.fillPrimes(sieve, primes);
            TreeSet<Integer> primeSet = new TreeSet<>(primes);
            for (int i = 1; i <= 1000; i++) {
                int d = n * i + 1;
                if (!primeSet.contains(d)) {
                    out.println(i);
                    return;
                }
            }
        }

    }

    static class Primes {
        public static void generateSieve(boolean[] sieve) {
            int n = sieve.length;
            Arrays.fill(sieve, true);
            sieve[0] = sieve[1] = false;
            for (int i = 2; (long) i * i < n; i++) {
                if (sieve[i]) {
                    for (int j = i * i; j < n; j += i) {
                        sieve[j] = false;
                    }
                }
            }
        }

        public static void fillPrimes(boolean[] sieve, ArrayList<Integer> primes) {
            for (int i = 0; i < sieve.length; i++) {
                if (sieve[i]) {
                    primes.add(i);
                }
            }
        }

    }

    static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner(InputStream inputStream) {
            br = new BufferedReader(new InputStreamReader(inputStream));
        }

        public String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

    }
}