#include <iostream>
#include <math.h>
using namespace std;

int main(){
  int n ,x=0 ,hoge[1000000]={} ,ans=0;
  while( cin >> n ){
    for( int i=2 ; i<=sqrt(n) ; i++ ){
      for( int j=i*2 ; j<=n ; j+=i ){
	hoge[j] = 1;
      }
    }
    
    for( int i=2 ; i<=n ; i++ ){
      if( hoge[i] == 0 ) ans++;
    }
    cout << ans << endl;
    ans = 0;
  }
}
  
### Prompt

Please create a solution in cpp to 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>
#include <math.h>
using namespace std;

int main(){
  int n ,x=0 ,hoge[1000000]={} ,ans=0;
  while( cin >> n ){
    for( int i=2 ; i<=sqrt(n) ; i++ ){
      for( int j=i*2 ; j<=n ; j+=i ){
	hoge[j] = 1;
      }
    }
    
    for( int i=2 ; i<=n ; i++ ){
      if( hoge[i] == 0 ) ans++;
    }
    cout << ans << endl;
    ans = 0;
  }
}
  
```