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 javax.print.attribute.HashDocAttributeSet;
import java.io.*;
import java.util.*;

public class Main{
    static boolean isPrimes[];
    static int max = 1000001;
    public static void main(String[] args) {
        MyScanner scanner = new MyScanner();
        isPrimes = new boolean[ max ];
        isPrimes[1] = false;
        isPrimes[2] = true;
        Arrays.fill( isPrimes, true);
        for( int i = 2 ; i < max ; i++ )
        {
            if( isPrimes[2] )
            {
                for ( int j = 2 * i ; j < max; j=j+i )
                {
                    isPrimes[j] = false;
                }
            }
        }
        int n = scanner.nextInt();
        for( int i = 1 ; i < 1001 ; i++ )
        {
            int val = ( n * i ) + 1;
            if( !isPrimes[ val ] )
            {
                System.out.println(i);
                return;
            }
        }
    }
}

class MyScanner {
    BufferedReader br;
    StringTokenizer st;

    public MyScanner() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    public int mod(long x) {
        // TODO Auto-generated method stub
        return (int) x % 1000000007;
    }

    public int mod(int x) {
        return x % 1000000007;
    }

    boolean hasNext() {
        if (st.hasMoreElements())
            return true;
        try {
            st = new StringTokenizer(br.readLine());
        } catch (IOException e) {
            e.printStackTrace();
        }
        return st.hasMoreTokens();
    }

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

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

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

    String nextLine() {
        String str = "";
        try {
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }
    public int[] readIntArray( int n )
    {
        int ar[] = new int[ n ];
        for( int i = 0;  i < n ; i++ )
            ar[ i ] = this.nextInt();
        return ar;
    }
    public long nextLong() {
        return Long.parseLong(next());
    }
}