#include<iostream>
using namespace std;
int prime[1200000];
int main(){
	for(int i=2;i<1200000;i++)prime[i]=1;
	for(int i=2;i*i<1200000;i++){
		for(int j=i*i;j<1200000;j+=i){
			prime[j]=0;
		}
	}
	for(int i=2;i<1200000;i++)prime[i]+=prime[i-1];
	int n;
	while(cin>>n){
		cout<<prime[n]<<endl;
	}
}
### 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 prime[1200000];
int main(){
	for(int i=2;i<1200000;i++)prime[i]=1;
	for(int i=2;i*i<1200000;i++){
		for(int j=i*i;j<1200000;j+=i){
			prime[j]=0;
		}
	}
	for(int i=2;i<1200000;i++)prime[i]+=prime[i-1];
	int n;
	while(cin>>n){
		cout<<prime[n]<<endl;
	}
}
```