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(){

	long n; cin >> n;
	long r=0;
	for(int i=1; i<n; i++){
		r+=(n-1)/i;
	}
	cout << r;
}