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, s=0;
	cin >> n;
	
	for(int i=1; i<=n; i++){
		s += n/i;
		if(n%i==0) s--;
	}
	cout << s;
	return 0;
}