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.*;
public class Main {
  //公式解説見たバージョン
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int N = scan.nextInt();
    int allcount = 0;
    for(int i = 1; i < N; i++){
      allcount += (N-1) / i;
    }

    System.out.println(allcount);	
  }
  //これは思いつかなかったです！！Cで回す必要すらないとは…
}