#include<iostream>
#include<vector>
using namespace std;

int main()
{
	long int n,m;
	while(cin>>n){
		vector<int> number(1000000,0);
		int ans=0;

		for(int i=2;i<=n;i++){
			if(number[i]==0){
				ans++;
				//cout<<i<<endl;
				for(m=i;m<=n;m+=i){
					number[m]=1;
				}
			}
		}
		cout<<ans<<endl;
	}
}
### 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<iostream>
#include<vector>
using namespace std;

int main()
{
	long int n,m;
	while(cin>>n){
		vector<int> number(1000000,0);
		int ans=0;

		for(int i=2;i<=n;i++){
			if(number[i]==0){
				ans++;
				//cout<<i<<endl;
				for(m=i;m<=n;m+=i){
					number[m]=1;
				}
			}
		}
		cout<<ans<<endl;
	}
}
```