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.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();

		int[] c = new int[(int) 1e6+1];
		
		/*
		 * a * b + c = n
		 * n / b = a ... c
		 */
		long ans = 0;
		for( int i=1 ; i<n ; i++ ) {
			int n2 = n/i + ( n%i != 0 ? 1 : 0) - 1;
			ans+= n2;
		}
		
		System.out.println(ans);
		

	}

}

