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.

//Where there is a will, there is a way!

import java.util.*;
import java.io.*;

public class Solution {
	public static void main (String[] args) throws IOException {
		
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw=new PrintWriter(System.out);
		StringTokenizer st;
                /*
                   inputCopy
inputCopy
5
outputCopy
1
inputCopy
4
outputCopy
2
                */
                long n=Long.parseLong(br.readLine());
                int limit=(int)1e5+1;
                boolean [] prime=new boolean[limit];
                Arrays.fill(prime,true);
                prime[0]=prime[1]=false;
                for(int i=2;i<=Math.sqrt(limit);++i)
                {
                    if(prime[i])
                    {
                        for(int j=2;i*j<limit;++j)
                        {
                            prime[i*j]=false;
                        }
                    }
                }
                long ans=1;
                for(int i=2;i<limit;++i)
                {
                    if(prime[i] && n%i==0)
                    {
                        ans=n/i;
                        break;
                    }
                }
                pw.println(ans);
                pw.flush();
                pw.close();
        }
}