#include<bits//stdc++.h>
using namespace std;
int a[1000500];
int main(){
	for(int i=2;i*i<1000500;i++){
		for(int j=i*2;j<1000500;j+=i){
			a[j]=1;
		}
	}
	int b;
	while(cin>>b){
		int c=0;
		for(int i=2;i<=b;i++){
			if(a[i]==0) c++;
		}
		cout<<c<<endl;
	}
}
### 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<bits//stdc++.h>
using namespace std;
int a[1000500];
int main(){
	for(int i=2;i*i<1000500;i++){
		for(int j=i*2;j<1000500;j+=i){
			a[j]=1;
		}
	}
	int b;
	while(cin>>b){
		int c=0;
		for(int i=2;i<=b;i++){
			if(a[i]==0) c++;
		}
		cout<<c<<endl;
	}
}
```