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 {

    Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        new Main().run();
    }

    void run() {

        int n = sc.nextInt();

        long cnt = 0;

        for (int i=1; i<n; i++) {
            int a = i;
            int diff = n - a;
            int tmpC = (diff % a == 0) ? diff / a : diff / a + 1;
            cnt += tmpC;
//            System.out.println(tmpC);
        }

        System.out.println(cnt);


    }


}

