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 IOException {
        final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int n = Integer.parseInt(br.readLine());
        long res = 0;

        for (int i = 1; i < n; ++i) {
            res += n / i - (n % i == 0 ? 1 : 0);
        }

        bw.write(Long.toString(res));

        bw.close();
        br.close();
    }
}
