#include<iostream>
using namespace std;
const int MAX=1000000;
bool t[MAX+1];
int c[MAX+1];

void make_table(){
	t[0]=t[1]=1;
  for(int i=0;i<=MAX;i++){
 	if(!t[i]){
 		for(int j=i+i;j<=MAX;j+=i)
 			t[j]=1;
 	}
  }
}
int main(){
  make_table();
  	int n; 
	for(int i=1;i<=MAX;i++){
		c[i]=(t[i])?c[i-1]:c[i-1]+1;
	}

	while(cin>>n)
		cout<<c[n]<<endl;
	
}
### Prompt

Construct a Cpp code solution to the problem outlined:

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;
const int MAX=1000000;
bool t[MAX+1];
int c[MAX+1];

void make_table(){
	t[0]=t[1]=1;
  for(int i=0;i<=MAX;i++){
 	if(!t[i]){
 		for(int j=i+i;j<=MAX;j+=i)
 			t[j]=1;
 	}
  }
}
int main(){
  make_table();
  	int n; 
	for(int i=1;i<=MAX;i++){
		c[i]=(t[i])?c[i-1]:c[i-1]+1;
	}

	while(cin>>n)
		cout<<c[n]<<endl;
	
}
```