#include <iostream>
using namespace std;
int a[1000000][2];
int main()
{
  int i,j,k,n;
  k = 0;
  for(i=2;i<1000000;i++){
    if(!a[i][0]){
      k++;
      for(j=2;i*j<1000000;j++){
	a[i*j][0] = 1;
      }
    }
    a[i][1] = k;
  }
  while(cin >> n){
    cout << a[n][1] << endl;
  }
  return 0;
}
### Prompt

Please formulate 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;
int a[1000000][2];
int main()
{
  int i,j,k,n;
  k = 0;
  for(i=2;i<1000000;i++){
    if(!a[i][0]){
      k++;
      for(j=2;i*j<1000000;j++){
	a[i*j][0] = 1;
      }
    }
    a[i][1] = k;
  }
  while(cin >> n){
    cout << a[n][1] << endl;
  }
  return 0;
}
```