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 t,i,j,k,a,b,c=0,d=0,n;
  scanf("%lld",&n);
  for(i=1;i<n;i++)
  c+=(n-1)/i;
printf("%lld\n",c);
  return 0;
}
