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 { 
  public static void main(String[] args) {

    Scanner scanner = new Scanner(System.in);
    int N = Integer.parseInt(scanner.next());
    scanner.close();
    int count = 0;
    int A = 1;
    boolean flag = false;

    for (int C = 1; C < N; C++){
      for (int B = 1; B <= (N - C) / B; B++){
        if ((N - C) % B == 0){
          if (B == (N - C) / B){
            count++;
            break;
          }
          count += 2;
        }
      }
    }

    System.out.println(count);
  }
}