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 {
  static Scanner in = new Scanner(System.in);
  public static void main(String[] args) {
    int n = in.nextInt();
    long ans = 0;
    for (long i = 1; i <= n; i++) {
      for (long j = 1; j * i < n; j++) {
        ans++;
      }
    }
    System.out.println(ans);

  }
}
