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.Scanner;
import java.util.Arrays;
/* Name of the class has to be "Main" only if the class is public. */
public class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		try {
		    Scanner sc = new Scanner(System.in);
		    int t,n,k,s,m;
		    n=sc.nextInt();
		    m=n;
		    n--;
		   s=0;k=1;
		   while((n/k)>0)
		   {
		       s=s+n/k;
		       k++;
		 
		   }
		   System.out.println(s);
		} catch(Exception e) {
		}
	}
}
