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
public class Main {
	public static void main(String[] args) {
		var sc = new java.util.Scanner(System.in);
		var N = sc.nextInt();

		long count = 0;
		for (int A = 1; A <= N-1; A++) {
				count+=(N-1)/A;
		}
		System.out.println(count);
	}
}
