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>
using namespace std;
int main(){
int n;
  int count=0;
  cin>>n;
  for(int a=1;a<=n-1;a++){
  for(int b=1;b<=(n-1)/a;b++){
  count++;
  }
  }
  cout<<count;
}
