#include<iostream>
using namespace std;
int a[1000000]={0};
int main(){
    int n,c=0;
    for(int i=2;i<10000;i++)
        for(int j=i;j*i<1000000;j++)
            a[i*j]=1;
    while(cin>>n){
        c=0;
        for(int i=2;i<=n;i++)
            if(a[i]==0)
                c++;
        cout<<c<<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;
int a[1000000]={0};
int main(){
    int n,c=0;
    for(int i=2;i<10000;i++)
        for(int j=i;j*i<1000000;j++)
            a[i*j]=1;
    while(cin>>n){
        c=0;
        for(int i=2;i<=n;i++)
            if(a[i]==0)
                c++;
        cout<<c<<endl;
    }
}
```