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 n; cin >> n;
	int res = 0;
	for (int i = 1; i < n; i++)
		res += (n - 1) / i;
	cout << res << '\n';
    return 0;
}