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;
using ll=long long;
ll N;
int main(){
  cin>>N;
  ll ans=0;
  for(ll i=1;i<=N-1;i++)
    ans+=(N-1)/i;
  cout<<ans<<endl;
  return 0;
}