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<iostream>
using namespace std;
 
int main(void){
	int n;
	int a = 0;
  	cin >> n;
  	for(int i = 1; i < n; i++){
    	a = a + (n-1)/i;
    }
	cout << a << endl;
}