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 n, ans=0;
    cin>>n;
    n--;
    for(int i=1;i<=n;++i)
    ans += (n/i);
    cout<<ans<<endl;
    return 0;
}