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 scn = new Scanner(System.in);
        int N = scn.nextInt();

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

    }
}