#include <iostream>

using namespace std;

#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)

int main(){
	int n;
	while(cin >> n){
		bool bin[1000000] = {};
		int m = 0;
		FOR(i,2,n+1)if(!bin[i]){
			REP(j,n/i+1)bin[i*j] = true;
			m++;
		}
		cout << m << 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;

#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)

int main(){
	int n;
	while(cin >> n){
		bool bin[1000000] = {};
		int m = 0;
		FOR(i,2,n+1)if(!bin[i]){
			REP(j,n/i+1)bin[i*j] = true;
			m++;
		}
		cout << m << endl;
	}
	return 0;
}
```