#include<iostream>
using namespace std;

inline int isPrime(int x){
  if(x<=1)return 0;
  for(int i=2;i*i<=x;i++){
    if(x%i==0)return 0;
  }
  return 1;
}

int p[1001000];
int main(){
  for(int i=1;i<1000000;i++){
    p[i] = p[i-1] + isPrime(i);
  }

  int n;
  while(cin >> n){
    cout << p[n] << 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>
using namespace std;

inline int isPrime(int x){
  if(x<=1)return 0;
  for(int i=2;i*i<=x;i++){
    if(x%i==0)return 0;
  }
  return 1;
}

int p[1001000];
int main(){
  for(int i=1;i<1000000;i++){
    p[i] = p[i-1] + isPrime(i);
  }

  int n;
  while(cin >> n){
    cout << p[n] << endl;
  }
}
```