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.io.*;
import java.util.*;
public class Main {
    public static void main(String[] args)throws Exception {
        BufferedReader buffer = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(buffer.readLine());
        long cnt = 0;
        for (int fact = 1; fact <= n ; fact++) {
            cnt+=n/fact;
            if (n%fact == 0)
                cnt--;
        }
        System.out.println(cnt);
    }
}
