You are given an integer number n. The following algorithm is applied to it:

  1. if n = 0, then end algorithm; 
  2. find the smallest prime divisor d of n; 
  3. subtract d from n and go to step 1. 



Determine the number of subtrations the algorithm will make.

Input

The only line contains a single integer n (2 ≤ n ≤ 10^{10}).

Output

Print a single integer — the number of subtractions the algorithm will make.

Examples

Input


5


Output


1


Input


4


Output


2

Note

In the first example 5 is the smallest prime divisor, thus it gets subtracted right away to make a 0.

In the second example 2 is the smallest prime divisor at both steps.
/*input
25
*/
import java.util.List;
import java.util.Arrays;
import java.util.ArrayList;
import java.io.OutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;
import java.util.Collection;
/*      
 * @uthor masterbios
 */
public class B{
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskAA solver = new TaskAA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskAA {
    	List <Long> list = new ArrayList<>();
        public void solve(int testNumber, InputReader in, PrintWriter out) {
    	   long n = in.nextLong();
    		primeFactors(n);
            list.sort(null);
            // int count = 0;
            // while(n > 0){
            //     for(long x : list){
            //         if(n % x == 0){
            //             n -= x;
            //             count++;
            //             break;
            //         }
            //     }
                    
            // }
            out.println(n/list.get(0));
    		
        }
        public void primeFactors(long n) 
    {
        
        while (n%2==0) 
        { 
           list.add(2L);
            n /= 2; 
        } 
  
      
        for (long i = 3; i <= Math.sqrt(n); i+= 2) 
        { 
             
            while (n%i == 0) 
            { 
               list.add(i);
                n /= i; 
            } 
        } 
  
        if (n > 2) 
            list.add(n);
        } 
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;
 
        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }
 
        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreElements()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }
        
        public String nextLine(){
            String s ="";
            try{
                s = reader.readLine();
            }
            catch(IOException e){
                throw new RuntimeException(e);
            }
            return s;
        }
        public int nextInt() {
            return Integer.parseInt(next());
        }
        public long nextLong() {
            return Long.parseLong(next());
        }
        public Double nextDouble() {
            return Double.parseDouble(next());
        }
        public char nextChar() {
            return next().charAt(0);
        }
        public float nextFloat(){
            return Float.parseFloat(next());
        }
        
    }
}     