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 sc = new Scanner(System.in);
		long N = sc.nextLong();

		sc.close();
		long count = 0;

		label: for (int a = 1; a < N; a++) {
			for (int b = 1; b < N; b++) {
				if (a * b < N) {
					count++;
				} else {
					continue label;
				}

			}
		}

		System.out.print(count);
	}

}