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();

        int count = 0;
        for (int A = 1; A<N  ; A++) {//A
            count+= (N-1)/A;
        }


        System.out.println(count);

    }

}
