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 n;
int ans;

int main()
{
	cin>>n;
	for(int i=1;i<n;i++)
		for(int j=1;j*i<n;j++)
			ans++;
	cout<<ans<<endl;
}