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.*;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		
		long count = 0;
		int c;
		for(int a = 1; a < n; a++){
			for(int b = 1; a*b < n; b++){
				c = n - a*b;
				if((a*b)+c==n && c > 0) count++;
			}
		}
		System.out.println(count);
	}
}