#include <iostream>
#include <vector>
using namespace std;

#define N 1000000
int main() {
  vector<int> table(N,1);
  table[0]=table[1]=0;
  for (int i=2; i*i<N; i++)
    if (table[i])
      for (int j=i*2; j<N; j+=i)
        table[j] = 0;
  int n;
  while(cin>>n) {
    int ans=0;
    for (int i=2;i<=n;i++) {
      if (table[i]) ans++;
    }
    cout << ans << endl;
  }
}
### 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>
#include <vector>
using namespace std;

#define N 1000000
int main() {
  vector<int> table(N,1);
  table[0]=table[1]=0;
  for (int i=2; i*i<N; i++)
    if (table[i])
      for (int j=i*2; j<N; j+=i)
        table[j] = 0;
  int n;
  while(cin>>n) {
    int ans=0;
    for (int i=2;i<=n;i++) {
      if (table[i]) ans++;
    }
    cout << ans << endl;
  }
}
```