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;
  cin >> N;
  int64_t ans=0;
  for(int i=1;i<N;i++){
    ans+=(N+i-1)/i-1;
  }
  cout << ans << endl;
  return 0;
}
