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 i,j,k,l,m,n,t,z,sum,x,y;
cin>>n;x=0;
for(i=1;i<n;i++)
{y=n/i;if(n%i==0)y=y-1;
x=x+y;}
cout<<x;
return 0;}
