#include<iostream>
#include<string>
#include<math.h>
using namespace std;

bool p[1000000];

int main(){
	int c,n;
	while(cin >> n){
		c = 0;
		for(int i = 2; i <= sqrt(n); i++){
			for(int j = 2; i * j <= n; j++){
				p[i*j] = true;
			}
			
		}
		for(int i = 2; i <= n; i++){
			if(p[i] == 0){
				c++;
				
			}
		}
		cout << c << 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>
#include<string>
#include<math.h>
using namespace std;

bool p[1000000];

int main(){
	int c,n;
	while(cin >> n){
		c = 0;
		for(int i = 2; i <= sqrt(n); i++){
			for(int j = 2; i * j <= n; j++){
				p[i*j] = true;
			}
			
		}
		for(int i = 2; i <= n; i++){
			if(p[i] == 0){
				c++;
				
			}
		}
		cout << c << endl;
	}
	
	return 0;
}
```