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 {
    public static void main(String[] args){
      // 入力
      Scanner sc = new Scanner(System.in);
      int N = sc.nextInt();
      
      // カウント
      int count = 0;
      for(long A = 1L; A < N; A++){
        for(long B = 1L; B <= A; B++){
          if(A*B < N){
            if(A != B){
              count += 2;
            }else{
              count++;
            }
          }else{
            break;
          }
        }
      }
      
      // 出力
      System.out.println(count);
    }
    
}