#include <iostream>
using namespace std;

int main()
{
	const int N = 1000000;
	static bool P[N];
	for ( int i=2; i<N; i++)
		P[i]=true;
	for(int i=2; i*i<N; i++ )
	if(P[i])
		for(int j=i+i;j<N;j+=i)
			P[j]=false;

	int n;
	while(cin>>n)
	{
		int c=0;
		for ( int i=0; i<=n; i++ )
			if (P[i])
				c++;
		cout<< c<<endl;
	}
	return 0;

}
### Prompt

Please create a solution in CPP 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>
using namespace std;

int main()
{
	const int N = 1000000;
	static bool P[N];
	for ( int i=2; i<N; i++)
		P[i]=true;
	for(int i=2; i*i<N; i++ )
	if(P[i])
		for(int j=i+i;j<N;j+=i)
			P[j]=false;

	int n;
	while(cin>>n)
	{
		int c=0;
		for ( int i=0; i<=n; i++ )
			if (P[i])
				c++;
		cout<< c<<endl;
	}
	return 0;

}
```