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,ans=0;
  cin >> n;
  for(int a=1; a<=n-1; a++)
  for(int b=1; a*b<=n-1; b++)
  ans++;
  cout << ans;
  return 0;
}