#include<iostream>
using namespace std;

int main(void){
  int n;
  while(cin >> n){
    int nums[n];
    int prime=0;
    for(int i=1;i<=n;i++){
      nums[i]=i;
    }
    for(int i=1;i<=n;i++){
      if(nums[i]>1){
	prime++;
	for(int j=2;nums[i]*j<=n;j++){
	  nums[nums[i]*j]=1;
	}
      }
    }
    cout << prime << endl;
  }
  
  return 0;
}
### Prompt

Please provide a cpp coded solution to the problem described below:

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 main(void){
  int n;
  while(cin >> n){
    int nums[n];
    int prime=0;
    for(int i=1;i<=n;i++){
      nums[i]=i;
    }
    for(int i=1;i<=n;i++){
      if(nums[i]>1){
	prime++;
	for(int j=2;nums[i]*j<=n;j++){
	  nums[nums[i]*j]=1;
	}
      }
    }
    cout << prime << endl;
  }
  
  return 0;
}
```