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);

		int n = sc.nextInt();

		long ans =0;;
		for (int i=1; i<=n; i++){
			ans += (n-1) / i;
		}
		System.out.println(ans);
	}

}