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);
    long N = (long)sc.nextInt();
    long Ans=0;
    for(int i=1;i<N;i++){
      if(N%i==0){
        Ans+=N/i-1;
      }else{
        Ans+=N/i;
      }
    }
    System.out.println(Ans);
  }
}