#include<iostream>
#include<vector>
#include<string>
#define T 1000000
using namespace std;

signed main() {
	vector<bool>hantei(T, true);
	vector<int>sosuu(T);
	int s = 0;
	for (int a = 2; a < T; a++) {
		if (hantei[a]) {
			s++;
			for (int b = a * 2; b < T; b+=a)hantei[b] = false;
		}
		sosuu[a]=s;
	}
	while (cin >> s)cout << sosuu[s] << endl;
}
### Prompt

Please formulate 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>
#include<vector>
#include<string>
#define T 1000000
using namespace std;

signed main() {
	vector<bool>hantei(T, true);
	vector<int>sosuu(T);
	int s = 0;
	for (int a = 2; a < T; a++) {
		if (hantei[a]) {
			s++;
			for (int b = a * 2; b < T; b+=a)hantei[b] = false;
		}
		sosuu[a]=s;
	}
	while (cin >> s)cout << sosuu[s] << endl;
}
```