#include <iostream>
#define MAX_N 1000000
using namespace std;

int main(){
	int n;
	bool num[MAX_N];
	for(int i=0;i<MAX_N;i++) num[i]=false; 

	while(cin>>n){
		int ans=0;
		for(int i=2;i<=n;i++){
			if(num[i]) continue;
			for(int j=2;j<=n/i;j++) num[i*j]=true;
			ans++;
		}
		cout<<ans<<endl;
	}
	return 0;
}
### Prompt

Your task is to create 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 <iostream>
#define MAX_N 1000000
using namespace std;

int main(){
	int n;
	bool num[MAX_N];
	for(int i=0;i<MAX_N;i++) num[i]=false; 

	while(cin>>n){
		int ans=0;
		for(int i=2;i<=n;i++){
			if(num[i]) continue;
			for(int j=2;j<=n/i;j++) num[i*j]=true;
			ans++;
		}
		cout<<ans<<endl;
	}
	return 0;
}
```