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