#include<iostream>

using namespace std;
bool prime(int x){
	if(x==2)return true;
	if(x==3)return true;
	for(int i=2;i*i<=x;i++){
		if(x%i==0)return false;
	}
	return true;
}
int main(){
	int data[1000000];
	data[0]=0,data[1]=0;
	for(int i=2;i<1000000;i++){
		if(prime(i))data[i]=data[i-1]+1;
		else data[i]=data[i-1];
	}
	int n;
	while(cin>>n)cout<<data[n]<<endl;
}
### Prompt

Develop a solution in Cpp to the problem described below:

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 prime(int x){
	if(x==2)return true;
	if(x==3)return true;
	for(int i=2;i*i<=x;i++){
		if(x%i==0)return false;
	}
	return true;
}
int main(){
	int data[1000000];
	data[0]=0,data[1]=0;
	for(int i=2;i<1000000;i++){
		if(prime(i))data[i]=data[i-1]+1;
		else data[i]=data[i-1];
	}
	int n;
	while(cin>>n)cout<<data[n]<<endl;
}
```