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.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.*;

public class A {
    public static void main(String[] args) {
//        Scanner sc = new Scanner(System.in);
        FastScanner sc = new FastScanner();

        boolean[] isPrime = sieve(1_000_010);
        int n = sc.nextInt();
        for (int i = 1; i <= 1000; i++) {
            if (!isPrime[i*n+1]) {
                System.out.println(i);
                return;
            }
        }
        throw new Error();
    }

    /* returns boolean array a[] such that a[p] == true iff p is prime. */
    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;
    }

    /* generate all prime numbers from 2..N, inclusive */
    static int [] generatePrimes(int N) {
        List<Integer> primes = new ArrayList<Integer>();
        boolean [] isPrime = sieve(N);
        for (int i = 0; i <= N; i++)
            if (isPrime[i])
                primes.add(i);
        int [] pa = new int[primes.size()];
        for (int i = 0; i < pa.length; i++)
            pa[i] = primes.get(i);
        return pa;
    }

    static void sort(int[] arr) {
        Random rng = new Random();
        int length = arr.length;
        for (int idx = 0; idx < arr.length; idx++) {
            int toSwap = idx + rng.nextInt(length-idx);
            int tmp = arr[idx];
            arr[idx] = arr[toSwap];
            arr[toSwap] = tmp;
        }
        Arrays.sort(arr);
    }

    public static class FastScanner {
        BufferedReader br;
        StringTokenizer st;
        public FastScanner(Reader in) {
            br = new BufferedReader(in);
        }
        public FastScanner() {
            this(new InputStreamReader(System.in));
        }
        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }
        int nextInt() {
            return Integer.parseInt(next());
        }
        long nextLong() {
            return Long.parseLong(next());
        }
        double nextDouble() {
            return Double.parseDouble(next());
        }
        String readNextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
        int[] readIntArray(int n) {
            int[] a = new int[n];
            for (int idx = 0; idx < n; idx++) {
                a[idx] = nextInt();
            }
            return a;
        }
        long[] readLongArray(int n) {
            long[] a = new long[n];
            for (int idx = 0; idx < n; idx++) {
                a[idx] = nextLong();
            }
            return a;
        }
    }
}