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 <stdio.h>

int main()
{
	int a;
	scanf("%d",&a);
	long long int ans = 0;
	for(int i=1;i<a;i++)
	{
		int s = 1;
		int t = (a-1)/i;
		ans += (t-s+1);
	}
	printf("%lld",ans);
}