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;
typedef long long ll;
int main() {
	ll N;
	cin >> N;
	ll r = 0;
	for (int i = 1; i < N; ++ i) {
		r += (N-1) / i;
	}
	cout << r << endl;
}
