#include<iostream>
#include<algorithm>
using namespace std;
#define MAX 1000000
int p[MAX];
void f(){
	int n=0;
	for(int i=2;i<MAX;i++){
		if(p[i]==0){
			p[i] = ++n;
			for(int j=2;j*i<MAX;j++)
				p[j*i] = -1;
		}
		else p[i] = n;
	}
} 
int main(){
	int n;
	f();
	while(cin>>n){	
		cout<<p[n]<<endl;
	}
	return 0;
}
### 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<algorithm>
using namespace std;
#define MAX 1000000
int p[MAX];
void f(){
	int n=0;
	for(int i=2;i<MAX;i++){
		if(p[i]==0){
			p[i] = ++n;
			for(int j=2;j*i<MAX;j++)
				p[j*i] = -1;
		}
		else p[i] = n;
	}
} 
int main(){
	int n;
	f();
	while(cin>>n){	
		cout<<p[n]<<endl;
	}
	return 0;
}
```