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.*;
import java.io.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double n = sc.nextInt();
        long sum = 0;
        for(int i=1;i<n;i++){
            int one = 0;
            if(n%i==0)one=1;
            int tmp=(int)n/i-one;
            sum+=tmp;
        }
        System.out.println(sum);
    }
}
