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;

public class Main {


    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int N=scan.nextInt();
        int p=0;
for(int a=1;a<N;a++){
    for(int b=1;a*b<N;b++){p++;}
}

System.out.println(p);
    }
}

