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,n1,ans=0;scanf("%d",&n),n1=sqrt(--n);
	for(int i=1;i<=n1;i++)
		ans+=(n/i)-i+1;
	printf("%d",ans*2-n1);
	return 0;
} 