#include <iostream>
using namespace std;

int pri[1000000]={0};


int main(){
	
	pri[0]=pri[1]=1;
	for(int i=2;i*i<=999999;i++){
		for(int j=i*2;pri[i]==0&&j<=999999;j+=i){
			pri[j]=1;
		}
	}
	
	int n;
	while(cin>>n){
		int tmp=0;
		for(int i=0;i<=n;i++){
			if(pri[i]==0)tmp++;
		}
		cout<<tmp<<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 pri[1000000]={0};


int main(){
	
	pri[0]=pri[1]=1;
	for(int i=2;i*i<=999999;i++){
		for(int j=i*2;pri[i]==0&&j<=999999;j+=i){
			pri[j]=1;
		}
	}
	
	int n;
	while(cin>>n){
		int tmp=0;
		for(int i=0;i<=n;i++){
			if(pri[i]==0)tmp++;
		}
		cout<<tmp<<endl;
	}
	
	return 0;
}

```