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 N, ct = 0;
  cin >> N;
  for (int a = 1; a < N; a++) {
    ct += (N - 1) / a;
  }
  cout << ct << endl;
}