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<cstdio>
int main(){
	int n;
	scanf("%d",&n);
	--n;
	int ans=0;
	for(int l=1,r;l<=n;l=r+1)
	{
		r=n/(n/l);
		ans+=(r-l+1)*(n/l);
	}
	printf("%d",ans);
	return 0;
}