#include<iostream>
#define max 1000010
using namespace std;

bool isp[max];
int ans[max]={};

void sieve(){
	for(int i=0;i<max;i++)isp[i]=true;
	for(int i=2;i<max;i++){
		if(isp[i]){
			ans[i]++;
			for(int j=2*i;j<max;j+=i)isp[j]=false;
		}
	}
	for(int i=1;i<max;i++)ans[i]+=ans[i-1];
	return;
}

int main()
{
	int n;

	sieve();
	while(cin>>n)cout<<ans[n]<<endl;

	return 0;
}
### 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>
#define max 1000010
using namespace std;

bool isp[max];
int ans[max]={};

void sieve(){
	for(int i=0;i<max;i++)isp[i]=true;
	for(int i=2;i<max;i++){
		if(isp[i]){
			ans[i]++;
			for(int j=2*i;j<max;j+=i)isp[j]=false;
		}
	}
	for(int i=1;i<max;i++)ans[i]+=ans[i-1];
	return;
}

int main()
{
	int n;

	sieve();
	while(cin>>n)cout<<ans[n]<<endl;

	return 0;
}
```