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 = Integer.parseInt(sc.next());

		long result = 0;
		for (int a = 1; a < n; a++) {

			if (n % a == 0) {
				result += n / a - 1;
			} else {
				result += n / a;
			}
		}

		System.out.println(result);

	}
}
