#include<iostream>
using namespace std;
#define N 1000000
bool p[1000000];
int main(){
  int n;

  for(int i=0;i<N;i++)p[i]=true;
  p[0]=p[1]=false;

  for(int i=0;i<=N/2;i++)
    if(p[i]==true)
      for(int j=i*2;j<N;j+=i)
	p[j]=false;

  while(cin>>n){
    int count=0;
    for(int i=0;i<=n;i++)
      if(p[i]==true)count++;
    cout<<count<<endl;
  }
  return 0;
}
### Prompt

Develop a solution in Cpp 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;
#define N 1000000
bool p[1000000];
int main(){
  int n;

  for(int i=0;i<N;i++)p[i]=true;
  p[0]=p[1]=false;

  for(int i=0;i<=N/2;i++)
    if(p[i]==true)
      for(int j=i*2;j<N;j+=i)
	p[j]=false;

  while(cin>>n){
    int count=0;
    for(int i=0;i<=n;i++)
      if(p[i]==true)count++;
    cout<<count<<endl;
  }
  return 0;
}
```