#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
#define REP(i,N) for(int i = 0; i < (int)N; i++)

int hako[1000100];
int main(){
	int n;
	while(cin >> n){
		int ret = 0;
		REP(i,1000100)hako[i] = 0;
		for(int i=2;i<=n;i++){
			if(hako[i] == 1)continue;
			ret++;
			for(int j=i;j <= n;j+=i){
				hako[j] = 1;
			}
		}
		cout << ret << endl;
	}
	return 0;
}
### Prompt

Create a solution in cpp for 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 <bits/stdc++.h>
using namespace std;
typedef long long LL;
#define REP(i,N) for(int i = 0; i < (int)N; i++)

int hako[1000100];
int main(){
	int n;
	while(cin >> n){
		int ret = 0;
		REP(i,1000100)hako[i] = 0;
		for(int i=2;i<=n;i++){
			if(hako[i] == 1)continue;
			ret++;
			for(int j=i;j <= n;j+=i){
				hako[j] = 1;
			}
		}
		cout << ret << endl;
	}
	return 0;
}
```