#include <iostream>
using namespace std;
const int MAX_N =1000000;
int main(){
	bool sosu[MAX_N]={};//false:sosu
	for(int i=2;i<MAX_N;i++){
		if(!sosu[i]){
			for(int j=2;j*i<MAX_N;j++){
				sosu[j*i]=true;
			}
		}
	}
	for(int n;cin>>n;){
		int ans=0;
		for(int i=2;i<=n;i++){
			if(!sosu[i])ans++;
		}
		cout<<ans<<endl;
	}
    return 0;
}
### Prompt

In CPP, your task is to solve 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;
const int MAX_N =1000000;
int main(){
	bool sosu[MAX_N]={};//false:sosu
	for(int i=2;i<MAX_N;i++){
		if(!sosu[i]){
			for(int j=2;j*i<MAX_N;j++){
				sosu[j*i]=true;
			}
		}
	}
	for(int n;cin>>n;){
		int ans=0;
		for(int i=2;i<=n;i++){
			if(!sosu[i])ans++;
		}
		cout<<ans<<endl;
	}
    return 0;
}
```