#include<iostream>
int main() {

  int n,i,j,c;
  while(std::cin>>n){
    c=0;
    int list[n-1];
    for(i=2;i<n+1;i++)list[i-2]=i;
    for(j=2;j*j<n+2;j++)
      if(list[j-2]!=0)
	for(i=1;j-2+list[j-2]*i<n;i++)
	  list[j-2+list[j-2]*i]=0;
    for(i=0; i<n-1; i++)
      if(list[i]!=0)c++;

    std::cout<<c<<"\n";
  }
}
### Prompt

Your challenge is to write 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>
int main() {

  int n,i,j,c;
  while(std::cin>>n){
    c=0;
    int list[n-1];
    for(i=2;i<n+1;i++)list[i-2]=i;
    for(j=2;j*j<n+2;j++)
      if(list[j-2]!=0)
	for(i=1;j-2+list[j-2]*i<n;i++)
	  list[j-2+list[j-2]*i]=0;
    for(i=0; i<n-1; i++)
      if(list[i]!=0)c++;

    std::cout<<c<<"\n";
  }
}
```