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) throws Exception {
        Scanner scan = new Scanner(System.in);
        String line = scan.nextLine();
        int answer = Integer.parseInt(line);

        int count = 0;
        for (int i = 1; i < answer; i++) {
            count += (answer -1) / i;
        }
        System.out.println(count);
    }
}
