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();
		int count =0;
		for(int i=1;i<=N;i++){
			for(int j=1;j*i<N;j++){
					count++;
			}		
		}
		
		System.out.println(count);
		
		
	}
}