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(){
  long long k,n;
  cin>>n;
  k=0;
  
  for (int i=1; i<n; i++){
  k += (n-1)/i;
    } 

    cout<<k<<endl;
  return 0;
}
