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>
#define ll long long
using namespace std;
int main()
{
  ll n,i,j,a,b,c,ans = 0;
  cin>>n;
  for(a = 1;a<n;a++)
  {
    ans += (n-1)/a;
  }
  cout<<ans;
}