#include <iostream>
using namespace std;

int Prime[1000000];

int main() {
	for(int i=0;i<1000000;++i)Prime[i]=1;
	
	Prime[0]=0;
	Prime[1]=0;
	
	for(int i=2;i<1000000;++i){
		if(Prime[i]){
			for(int j=i*2;j<1000000;j+=i){
				Prime[j]=0;
			}
		}
	}
	
	int n,cnt;
	while(cin>>n){
		cnt = 0;
		for(int i=0;i<=n;++i){
			cnt+=Prime[i];
		}
		cout<<cnt<<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 Prime[1000000];

int main() {
	for(int i=0;i<1000000;++i)Prime[i]=1;
	
	Prime[0]=0;
	Prime[1]=0;
	
	for(int i=2;i<1000000;++i){
		if(Prime[i]){
			for(int j=i*2;j<1000000;j+=i){
				Prime[j]=0;
			}
		}
	}
	
	int n,cnt;
	while(cin>>n){
		cnt = 0;
		for(int i=0;i<=n;++i){
			cnt+=Prime[i];
		}
		cout<<cnt<<endl;
	}
	
	return 0;
}
```