#include<iostream>
using namespace std;
int main(){
    int X,ans,count;
    bool num[1000001]={};
    for(int i=2;i<=1000000;i++){
        if(!num[i]) 
        for(int j=i*2;j<=1000000;j+=i)  num[j] = true;
    }
    while(cin >> X)
    {
        count = 0;
        for(int i=2;i<=X;i++){
            if(!num[i]) count++;
        }
        cout << count << endl;
    }
    return 0;
}

### Prompt

Please create a solution in cpp to 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 main(){
    int X,ans,count;
    bool num[1000001]={};
    for(int i=2;i<=1000000;i++){
        if(!num[i]) 
        for(int j=i*2;j<=1000000;j+=i)  num[j] = true;
    }
    while(cin >> X)
    {
        count = 0;
        for(int i=2;i<=X;i++){
            if(!num[i]) count++;
        }
        cout << count << endl;
    }
    return 0;
}

```