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.*;
import java.io.*;
import java.math.*;
public class Main {
    public static void main(String[]args){
		Scanner sc = new Scanner(System.in);
		PrintWriter ou = new PrintWriter(System.out);
		int n = Integer.parseInt(sc.next()) - 1;
		sc.close();
		long yono = 0;
		for(int i = 1 ; i <= n ; i++){
			yono += n / i;
		}
		ou.println(yono);
		ou.flush();
	}
}