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;
	int ans = 0;
	scanf("%d", &N);
	for (int i = 1; i <= N; i++)
	{
		ans += (N-1)/i;
	}
	printf("%d\n", ans);
	return 0;
}