#include<iostream>
using namespace std;

const int listmax=1000000;

int main(){
	bool nprime[listmax]={};
	for(int i=2;i<listmax;i++){
		if(nprime[i])continue;
		for(int j=i+i;j<listmax;j+=i){
			nprime[j]=true;
		}
	}
	int n;
	while(cin>>n){
		int sum=0;
		for(int i=2;i<=n;i++){
			if(!nprime[i])sum++;
		}
		cout<<sum<<endl;
	}
	return 0;
}
### 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<iostream>
using namespace std;

const int listmax=1000000;

int main(){
	bool nprime[listmax]={};
	for(int i=2;i<listmax;i++){
		if(nprime[i])continue;
		for(int j=i+i;j<listmax;j+=i){
			nprime[j]=true;
		}
	}
	int n;
	while(cin>>n){
		int sum=0;
		for(int i=2;i<=n;i++){
			if(!nprime[i])sum++;
		}
		cout<<sum<<endl;
	}
	return 0;
}
```