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() {
 float n;
cin>>n;
int ans=0;
for (float i = 1; i < n; i++)
{
   for(float j=1;j<n/i;j++)
{
ans++;
}}
cout<<ans<<endl;
}