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.io.*;
import java.util.*;
class Main
{
	 public static void  main (String[] args) throws IOException
    {
       try{
       BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
       int a=0;
       a=Integer.parseInt(br.readLine());
       long sum=0;int c=1;
       for(int i=1;i<=a;i++)
       {
       	sum+=(a-1)/i;
       }
       System.out.println(sum);
   }
    catch(Exception e){}
}}
