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) {
        try (Scanner sc = new Scanner(System.in)) {
            // Input
            int N = Integer.parseInt(sc.next());

            // Solve
            int count = 0;
            for (int a = 1; a < N; a++) {
                for (int b = 1; b < N; b++) {
                    if (a * b >= N) {
                        break;
                    }
                    count++;
                }
            }

            System.out.println(count);
        }
    }

}