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 K = sc.nextInt();
        long N = sc.nextLong();

        long res=0;

        for(int i=1; i<N; i++){
            res = res+ (N-1)/i;
        }
        
        System.out.println(res);
        }
    }