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<iostream>
int main(){
  int n;
  std::cin>>n;
  int ans = 0;
  for(int a=1;a<n;++a)
    ans += (n-1)/a;
  std::cout<< ans <<std::endl;
}