#include <iostream>
#include <vector>
using namespace std;

int a[1000000]={};

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

Develop a solution in Cpp 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 <vector>
using namespace std;

int a[1000000]={};

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