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 n;
long long ans;

int main()
{
	cin>>n;

	for(int a=1;a<n;a++)
		for(int b=1;a*b<n;b++)
			ans++;
	cout<<ans;
}