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