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