#include<iostream>
#include<algorithm>

using namespace std;

#define MAX 1000000

int p[MAX];

void fanc(void){
	int num = 0;
	for(int ix = 2;ix < MAX;++ix){
		if(p[ix] == 0){
			p[ix] = ++num;
			for(int jx = 2;jx*ix<MAX;++jx)
				p[jx*ix] = -1;
		}else
			p[ix] = num;
	}
}

int main()
{
	int n;
	fanc();
	while(cin >> n)
		cout <<p[n]<<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<algorithm>

using namespace std;

#define MAX 1000000

int p[MAX];

void fanc(void){
	int num = 0;
	for(int ix = 2;ix < MAX;++ix){
		if(p[ix] == 0){
			p[ix] = ++num;
			for(int jx = 2;jx*ix<MAX;++jx)
				p[jx*ix] = -1;
		}else
			p[ix] = num;
	}
}

int main()
{
	int n;
	fanc();
	while(cin >> n)
		cout <<p[n]<<endl;

	return 0;
}
```