#include <iostream>

using namespace std;
int main(){
	static bool cmp[1000000] = {true};
	static int ans[1000000];
	for(int i=2; i<1000000;i++){
		if(!cmp[i]){
			for(int j=2;j*i<1000000;j++){
				cmp[i*j] = true;
			}
		}
		ans[i] = ans[i-1]+!cmp[i];
	}
	for(int n; cin>>n; n++){
		cout<<ans[n]<<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(){
	static bool cmp[1000000] = {true};
	static int ans[1000000];
	for(int i=2; i<1000000;i++){
		if(!cmp[i]){
			for(int j=2;j*i<1000000;j++){
				cmp[i*j] = true;
			}
		}
		ans[i] = ans[i-1]+!cmp[i];
	}
	for(int n; cin>>n; n++){
		cout<<ans[n]<<endl;
	}
	return 0;
}
```