Given is a positive integer N. How many tuples (A,B,C) of positive integers satisfy A \times B + C = N?

Constraints

* 2 \leq N \leq 10^6
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N


Output

Print the answer.

Examples

Input

3


Output

3


Input

100


Output

473


Input

1000000


Output

13969985
import java.util.*;

public class Main{
  public static void main(String[] args)
  {
    Scanner sc=new Scanner(System.in);
    int n=sc.nextInt();
    long cnt=0;
    for(int i=1;i<n;i++)
    {
      for(int j=1;j<n;j++)
      {
        if(i*j>=n)
        break;
        cnt++;
      }
    }
    System.out.println(cnt);
  }
}

  