#include <iostream>
using namespace std;


int main() {

	int judge[1000000];
	for(int k=0;k<1000000;k++)judge[k]=1;
	int n,sum;
	
	while(cin>>n){
		if(n==0||n==1){
			sum = 0;
		}else{
			sum = 1;
			for(int i=3;i<n+1;i+=2){
				if (judge[i]==1){
					sum++;
					for(int j=2;j<=n/i;j++)
						judge[i*j] = 0;
				}	
			}
		}
		
		cout << sum <<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 <iostream>
using namespace std;


int main() {

	int judge[1000000];
	for(int k=0;k<1000000;k++)judge[k]=1;
	int n,sum;
	
	while(cin>>n){
		if(n==0||n==1){
			sum = 0;
		}else{
			sum = 1;
			for(int i=3;i<n+1;i+=2){
				if (judge[i]==1){
					sum++;
					for(int j=2;j<=n/i;j++)
						judge[i*j] = 0;
				}	
			}
		}
		
		cout << sum <<endl;
	}

	return 0;
}
```