#include<iostream>
using namespace std;

int main(){
	int n[1000000]={0};
	int tmp=0,a;
	
	n[0]=1;
	n[1]=1;
	for(int i=2;i<1000000;i++){
		for(int j=2;i*j<1000000&&n[i]!=1;j++){
			n[i*j]=1;
		}
	}
	
	while(cin>>a){
		tmp=0;
		for(int i=0;i<=a;i++){
			if(n[i]==0) tmp++;
		}
		cout<< tmp << endl;
	}
	return 0;
}
### Prompt

Please formulate 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>
using namespace std;

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