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 sc = new Scanner(System.in);
    int n = sc.nextInt();
    sc.close();
    System.out.println(solve(n - 1));
  }

  static int solve(int n){
    if(n == 1) {
      return 1;
    }
    int ans = 0;
    for(int i = 1; i <= n; i++){
      ans += n / i;
    }
    return ans;
  }
}