#include<bits/stdc++.h>
using namespace std;
int main(){
    bool p[1000000];int n,i,j;
    fill(p,p+1000000,1);p[0] = p[1] = 0;
    for(i=2;i<=999;i++){
        if(!p[i]) continue;
        for(j=i+i;j<1000000;j+=i) p[j] = 0;
    }
    while(cin >> n) cout << accumulate(p,p+n+1,0) << "\n";
}

### Prompt

Generate a CPP solution 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<bits/stdc++.h>
using namespace std;
int main(){
    bool p[1000000];int n,i,j;
    fill(p,p+1000000,1);p[0] = p[1] = 0;
    for(i=2;i<=999;i++){
        if(!p[i]) continue;
        for(j=i+i;j<1000000;j+=i) p[j] = 0;
    }
    while(cin >> n) cout << accumulate(p,p+n+1,0) << "\n";
}

```