#include<iostream>
#include<cstdio>
#include <cstring>
using namespace std;
int main()
{
	    int n;
		bool a[1000001]; 
		memset(a,0,sizeof(a));
		for(int i=2;i<=1000;++i)
		{
			for(int j=2;j*i<=1000000;++j)
			{
				a[i*j]=1;
			}
		}

	while(cin>>n)
	{
		int count=0;
		for(int k=2;k<=n;k++)
		{
			if(!a[k])
			count++;
		}
		cout<<count<<endl;
	
	
		
	}
	return 0;
}
### Prompt

Your task is to create 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<cstdio>
#include <cstring>
using namespace std;
int main()
{
	    int n;
		bool a[1000001]; 
		memset(a,0,sizeof(a));
		for(int i=2;i<=1000;++i)
		{
			for(int j=2;j*i<=1000000;++j)
			{
				a[i*j]=1;
			}
		}

	while(cin>>n)
	{
		int count=0;
		for(int k=2;k<=n;k++)
		{
			if(!a[k])
			count++;
		}
		cout<<count<<endl;
	
	
		
	}
	return 0;
}
```