#include <iostream>
#include <cmath>
using namespace std;

int arr[1000000];

int main()
{
	int x, cnt, j, i = 3;
	arr[2] = 1;
	for (; i < 1000000; ++i) {
		cnt = 1;
		for (j = 2; j <= sqrt(i); ++j) {
			if (i%j == 0) {
				arr[i] = arr[i - 1];
				--cnt;
				break;
			}
		}
		arr[i] = arr[i - 1] + cnt;
	}
	while (cin >> x) {
		cout << arr[x] << endl;
	}
	return 0;
}
### Prompt

Create a solution in cpp for 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>
#include <cmath>
using namespace std;

int arr[1000000];

int main()
{
	int x, cnt, j, i = 3;
	arr[2] = 1;
	for (; i < 1000000; ++i) {
		cnt = 1;
		for (j = 2; j <= sqrt(i); ++j) {
			if (i%j == 0) {
				arr[i] = arr[i - 1];
				--cnt;
				break;
			}
		}
		arr[i] = arr[i - 1] + cnt;
	}
	while (cin >> x) {
		cout << arr[x] << endl;
	}
	return 0;
}
```