#include <iostream>
using namespace std;
#define N 1000000
int a[N];
int main(){
	int i,j;
	a[0]=0;a[1]=0;
	for(i=2;i<N;i++){
		a[i]=1;
	}
	for(i=2;i<N/2+1;i++){
		j=2;
		while(i*j<N){
			a[i*j]=0;
			j+=1;
		}
	}
	int n;
	while(cin>>n){
		j=0;
		for(i=2;i<=n;i++){
			j+=a[i];
		}
		cout<<j<<endl;
	}
}
### 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 N 1000000
int a[N];
int main(){
	int i,j;
	a[0]=0;a[1]=0;
	for(i=2;i<N;i++){
		a[i]=1;
	}
	for(i=2;i<N/2+1;i++){
		j=2;
		while(i*j<N){
			a[i*j]=0;
			j+=1;
		}
	}
	int n;
	while(cin>>n){
		j=0;
		for(i=2;i<=n;i++){
			j+=a[i];
		}
		cout<<j<<endl;
	}
}
```