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.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.util.StringTokenizer;

public class Main {

    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        solver.solve(in, out);
        out.close();
    }
}

class Task {

    //    static int MAX = 1000001;
//    boolean[] w;
    //    long[] b;
//    boolean[] used;
//    List<Map<Integer, Integer>> g = new ArrayList<>();
//    List<List<Integer>> g = new ArrayList<>();
//    int n;
//    int m;


    public void solve(Scanner in, PrintWriter out) {
//        int[] res = new int[100001];
//        Arrays.fill(res, 0);
        int n = in.nextInt();
//        int m = in.nextInt();
//        int a[] = new int[n];
        for (int i = 1; i < 1000; i++) {
            int x = n * i + 1;
            if (!isPrime(x)) {
                System.out.println(i);
                return;
            }
        }

    }

    boolean isPrime(int x) {
        for (int i = 2; i * i <= x; i++) {
            if (x % i == 0) {
                return false;
            }
        }
        return true;
    }

}

class Utils {

    public static int binarySearch(int[] a, int key) {
        int s = 0;
        int f = a.length;
        while (f > s) {
            int mid = (s + f) / 2;
            if (a[mid] > key) {
                f = mid - 1;
            } else if (a[mid] <= key) {
                s = mid + 1;
            }
        }
        return -1;
    }
}

class Pair<T, U> {
    public T a;
    public U b;

    public Pair(T a, U b) {
        this.a = a;
        this.b = b;
    }

    @Override
    public boolean equals(Object obj) {
        Pair<T, U> p = (Pair<T, U>) obj;
        return p.a.equals(a) || p.a.equals(b);
    }

    @Override
    public int hashCode() {
        return 42;
    }
}


class Vect {
    public int a;
    public int b;

    public Vect(int a, int b) {
        this.a = a;
        this.b = b;
    }
}

class Triple<T, U, P> {
    public T a;
    public U b;
    public P c;

    public Triple(T a, U b, P c) {
        this.a = a;
        this.b = b;
        this.c = c;
    }
}


class Scanner {
    BufferedReader in;
    StringTokenizer tok;

    public Scanner(InputStream in) {
        this.in = new BufferedReader(new InputStreamReader(in));
        tok = new StringTokenizer("");
    }

    private String tryReadNextLine() {
        try {
            return in.readLine();
        } catch (Exception e) {
            throw new InputMismatchException();
        }
    }

    public String nextToken() {
        while (!tok.hasMoreTokens()) {
            tok = new StringTokenizer(next());
        }
        return tok.nextToken();
    }

    public String next() {
        String newLine = tryReadNextLine();
        if (newLine == null)
            throw new InputMismatchException();
        return newLine;
    }

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

    public long nextLong() {
        return Long.parseLong(nextToken());
    }
}