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
#include <bits/stdc++.h>
using namespace std;

int main() {
  int a;
  cin >> a;
  int s = 0;
  for(int i = 1; i < a; i++){
     int b = (a-1)/i;
     s += b;
  }
  cout << s << endl;
}