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.Scanner;

public class Main {
	
	public static void main(String[] args)
	{
		Scanner s=new Scanner(System.in);
		
		int n=s.nextInt();
		
		long ans=0;
		
		for(int i=1;i<1000001;i++)
		{
			if(n%i==0)
			{
				ans=ans+(n/i)-1;
			}
			else
			{
				ans=ans+(n/i);
			}
		}
		
		System.out.println(ans);
		
	}
	
}