#include <bits/stdc++.h>
using namespace std;

const int N = 1e6L + 11;
int p[N];
int sum[N];

int main() {
	iota(p, p + N, 0);
	for(int i = 2; i < N; i ++) if(p[i] == i)
		for(int j = i; j < N; j += i) p[j] = i;
	for(int i = 2; i < N; i ++)
		sum[i] = sum[i - 1] + (p[i] == i);
	ios :: sync_with_stdio(false);
	int n;
	while(cin >> n)
		cout << sum[n] << '\n';
	return 0;
}
### Prompt

Please provide a Cpp coded solution 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 <bits/stdc++.h>
using namespace std;

const int N = 1e6L + 11;
int p[N];
int sum[N];

int main() {
	iota(p, p + N, 0);
	for(int i = 2; i < N; i ++) if(p[i] == i)
		for(int j = i; j < N; j += i) p[j] = i;
	for(int i = 2; i < N; i ++)
		sum[i] = sum[i - 1] + (p[i] == i);
	ios :: sync_with_stdio(false);
	int n;
	while(cin >> n)
		cout << sum[n] << '\n';
	return 0;
}
```