#include<cstdio>
#include<iostream>
using namespace std;
int main(){ 
    int n;
    int prime[1000000];
    while(cin>>n){
    for(int i=0;i<1000000;i++)prime[i]=0;
    for(int i=2;i<=n;i++){ 
        for(int j=2;i*j<=n;j++){ 
            prime[i*j]=1;
        }
    }
    int ans=0;
    for(int i=2;i<=n;i++){
        if(prime[i]==0)ans++;
    }
    printf("%d\n",ans);
    }
}
### Prompt

Construct a cpp code solution to the problem outlined:

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<cstdio>
#include<iostream>
using namespace std;
int main(){ 
    int n;
    int prime[1000000];
    while(cin>>n){
    for(int i=0;i<1000000;i++)prime[i]=0;
    for(int i=2;i<=n;i++){ 
        for(int j=2;i*j<=n;j++){ 
            prime[i*j]=1;
        }
    }
    int ans=0;
    for(int i=2;i<=n;i++){
        if(prime[i]==0)ans++;
    }
    printf("%d\n",ans);
    }
}
```