#include<bits/stdc++.h>
using namespace std;
int n;
int ans[1000000];

int main(){
  for(int i=2;i<=999999;i++){
    ans[i]=ans[i-1];
    for(int j=2;j<=sqrt(i);j++){
      if(i%j==0)goto f;
    }
    ans[i]++;
    f:;
  }
  while(cin>>n){
    cout<<ans[n]<<endl;
  }

  return 0;
}


### Prompt

Create a solution in CPP for 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<bits/stdc++.h>
using namespace std;
int n;
int ans[1000000];

int main(){
  for(int i=2;i<=999999;i++){
    ans[i]=ans[i-1];
    for(int j=2;j<=sqrt(i);j++){
      if(i%j==0)goto f;
    }
    ans[i]++;
    f:;
  }
  while(cin>>n){
    cout<<ans[n]<<endl;
  }

  return 0;
}


```