#include<iostream>
using namespace std;
int main()
{
	bool p[1000000] = { false };
	int n;

	while (cin >> n){
		for (int i = 2; i <n ; i++){
			for (int i2 = 2; i*i2 <= n; i2++){
				p[i*i2] = true;
			}
		}
		p[2] = false;
		p[3] = false;
		int c = 0;
		for (int i = 2; i <= n; i++){
			if (!p[i])c++;
		}
		cout << c << endl;
	}
}
### Prompt

Your challenge is to write 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>
using namespace std;
int main()
{
	bool p[1000000] = { false };
	int n;

	while (cin >> n){
		for (int i = 2; i <n ; i++){
			for (int i2 = 2; i*i2 <= n; i2++){
				p[i*i2] = true;
			}
		}
		p[2] = false;
		p[3] = false;
		int c = 0;
		for (int i = 2; i <= n; i++){
			if (!p[i])c++;
		}
		cout << c << endl;
	}
}
```