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>
using namespace std;
int n,ans;
int main()
{
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
		for(int j=1;j*i<n;++j)
			++ans;
	printf("%d",ans);
	return 0;
}