#include <iostream>
using namespace std;
 
bool IsPrime(int n){
  for(int i=2;i*i<=n;i++){
    if(n%i==0) return false;
  }
  return true;
}

int main(){
  int n;
  int prime[1000000]={};
  for(int i=2;i<=1000000;i++){
      if(IsPrime(i)) prime[i]=prime[i-1]+1;
      else prime[i]=prime[i-1];
  }
   
  while(cin >> n) cout << prime[n]<< endl;

   
   return 0;
}


### Prompt

In cpp, your task is to solve the following problem:

Write a program which reads an integer n and prints the number of prime numbers which are less than or equal to n. A prime number is a natural number which has exactly two distinct natural number divisors: 1 and itself. For example, the first four prime numbers are: 2, 3, 5 and 7.



Input

Input consists of several datasets. Each dataset has an integer n (1 ≤ n ≤ 999,999) in a line.

The number of datasets is less than or equal to 30.

Output

For each dataset, prints the number of prime numbers.

Example

Input

10
3
11


Output

4
2
5

### Response

```cpp
#include <iostream>
using namespace std;
 
bool IsPrime(int n){
  for(int i=2;i*i<=n;i++){
    if(n%i==0) return false;
  }
  return true;
}

int main(){
  int n;
  int prime[1000000]={};
  for(int i=2;i<=1000000;i++){
      if(IsPrime(i)) prime[i]=prime[i-1]+1;
      else prime[i]=prime[i-1];
  }
   
  while(cin >> n) cout << prime[n]<< endl;

   
   return 0;
}


```