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;
  
  int res=0;
  for(int a=1; a<N; a++){
      res+=N/a-(N%a==0);
  }
  cout<<res<<endl;
}