#include<iostream>
using namespace std;
int n,p[1000000];
int main(){
	for(int i=0;i<1000000;++i)p[i]=1;
	p[0]=0;
	p[1]=0;
	for(int i=2;i<1000000,i*i<1000000;++i){
		for(int j=2;j<1000000;++j){
			if(p[i]==0)break;
			if(j%i==0 && i!=j)p[j]=0;
		}
	}
	while(cin>>n){
		int sum=0;
		for(int i=0;i<=n;++i)if(p[i]==1)++sum;
		cout<<sum<<endl;
	}
}
### Prompt

Your task is to create a CPP solution to 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 n,p[1000000];
int main(){
	for(int i=0;i<1000000;++i)p[i]=1;
	p[0]=0;
	p[1]=0;
	for(int i=2;i<1000000,i*i<1000000;++i){
		for(int j=2;j<1000000;++j){
			if(p[i]==0)break;
			if(j%i==0 && i!=j)p[j]=0;
		}
	}
	while(cin>>n){
		int sum=0;
		for(int i=0;i<=n;++i)if(p[i]==1)++sum;
		cout<<sum<<endl;
	}
}
```