#include<iostream>
using namespace std;
bool p[1000000]={true,true};
int main(){
  for(int i=2; i<1000; i++)
    if(!p[i])
      for(int j=i*i; j<1000000; j+=i)
	p[j] = true;
  int n;
  while(cin >>n){
    int solve = 0;
    for(int i=0; i<=n; i++)
      if(!p[i])
	solve++;
    cout <<solve<<endl;
  }
  return 0;
}
### 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;
bool p[1000000]={true,true};
int main(){
  for(int i=2; i<1000; i++)
    if(!p[i])
      for(int j=i*i; j<1000000; j+=i)
	p[j] = true;
  int n;
  while(cin >>n){
    int solve = 0;
    for(int i=0; i<=n; i++)
      if(!p[i])
	solve++;
    cout <<solve<<endl;
  }
  return 0;
}
```