#include <iostream>
using namespace std;

bool isprime(int n){
	if(n < 2)return false;
	
	for(int i=2;i*i<=n;i++)
		if( n%i == 0)return false;
	return true;
}
int main(){
	int n;
	bool memo[1000000] = {false};
	for(int i=0;i<1000000;i++){
		memo[i] = isprime(i);
	}
	while(cin >> n){
		int output = 0;
		for(int i=0;i<=n;i++){
			if(memo[i])output++;
		}
		cout << output << endl;
	}
}
### Prompt

Construct a Cpp code solution to the problem outlined:

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;

bool isprime(int n){
	if(n < 2)return false;
	
	for(int i=2;i*i<=n;i++)
		if( n%i == 0)return false;
	return true;
}
int main(){
	int n;
	bool memo[1000000] = {false};
	for(int i=0;i<1000000;i++){
		memo[i] = isprime(i);
	}
	while(cin >> n){
		int output = 0;
		for(int i=0;i<=n;i++){
			if(memo[i])output++;
		}
		cout << output << endl;
	}
}
```