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