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.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int count = 0;
    for (int i = 1; i < n; i++) {
      int a = i;
      for (int j = 1; i * j < n; j++) {
        int b = j;
        if (n - a * b > 0) {
          int c = n - a * b;
          count++;
        }
      }
    }
    System.out.println(count);
  }
}