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) {
		var sc = new Scanner(System.in);
		var n = sc.nextInt();
		sc.close();

		var sum = 0;
		for (var a = 1; a <= n; a++) {
			var count = n / a;
			if (n % a == 0) {
				count--;
			}
			sum += count;
		}
		System.out.println(sum);
	}
}
