#include <iostream>

#define rep(i, n) for(int i = 2; i < n; i ++)

using namespace std;

int main(void){
	const int N = (int)1e6;
	bool num[N];
	rep(i, N) num[i] = true;
	for(int i = 2; i * i < N; i ++) if(num[i]) for(int j = i; i * j < N; j ++) num[i * j] = false;

	for(int n, count = 0; cin >> n; cout << count << endl, count = 0)
		rep(i, n + 1) if(num[i]) count ++;

	return 0;
}
### Prompt

Develop a solution in cpp to the problem described below:

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 rep(i, n) for(int i = 2; i < n; i ++)

using namespace std;

int main(void){
	const int N = (int)1e6;
	bool num[N];
	rep(i, N) num[i] = true;
	for(int i = 2; i * i < N; i ++) if(num[i]) for(int j = i; i * j < N; j ++) num[i * j] = false;

	for(int n, count = 0; cin >> n; cout << count << endl, count = 0)
		rep(i, n + 1) if(num[i]) count ++;

	return 0;
}
```