#include <iostream>
using namespace std;

int main(){
	char nums[1000000];
	int n;
	for(int i = 2; i < 1000000; i++)
		nums[i] = 1;
	for(int j = 2; j < 1000; j++)

		for(int k = 2; j * k <= 1000000; k++)
			nums[j * k] = 0;
	while(cin >> n){
		int count = 0;
		for(int l = 2; l <= n; l++)
			if(nums[l])
				count++;
		cout << count << endl;
	}
	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>
using namespace std;

int main(){
	char nums[1000000];
	int n;
	for(int i = 2; i < 1000000; i++)
		nums[i] = 1;
	for(int j = 2; j < 1000; j++)

		for(int k = 2; j * k <= 1000000; k++)
			nums[j * k] = 0;
	while(cin >> n){
		int count = 0;
		for(int l = 2; l <= n; l++)
			if(nums[l])
				count++;
		cout << count << endl;
	}
	return 0;
}
```