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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		long n = Long.parseLong(br.readLine());

		long ans = 0;

		for (int a = 1; a < n; a++) {
			for (int b = 1; b < n; b++) {
				if (a * b >= n)
					break;
				ans++;
			}
		}
		System.out.println(ans);
	}
}
