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.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {

	static int MOD = 1000000007;

	public static void main(String[] args) {
		exec_1_3();

	}

	public static void exec_1_3() {

		try(var sc = new Scanner(System.in)) {


			int N = sc.nextInt();

			long ans =0;
			for(int i=1;i<N;i++) {

				int m =  (N-1)/i;
				ans += m;
			}
			System.out.println(ans);
		}
	}
}