#include <iostream>
using namespace std;
char s[1000004];
int  d[1000004];
int main( void )
{
  int M=1000000;
  int n=0;
  for( int i=2; i<M; i++ ){
    if( !s[i] ){
      int j=i*2;
      while( j < M ){ s[j]=1; j+=i; }
      n++;
    }
    d[i] = n;
  }
  while( 1 ){
    cin >> n;
    if( cin.eof() ) break;
    cout << d[n] << endl;
  }
  return 0;
}
### Prompt

Your task is to create a CPP solution 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>
using namespace std;
char s[1000004];
int  d[1000004];
int main( void )
{
  int M=1000000;
  int n=0;
  for( int i=2; i<M; i++ ){
    if( !s[i] ){
      int j=i*2;
      while( j < M ){ s[j]=1; j+=i; }
      n++;
    }
    d[i] = n;
  }
  while( 1 ){
    cin >> n;
    if( cin.eof() ) break;
    cout << d[n] << endl;
  }
  return 0;
}
```