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>
int main(){
	int n,ret=0,u,v,d=1;
	scanf("%d",&n);
	--n;
	while(d<=n){
		u=(n/d),v=n/u;
		ret += 1LL*(v-d+1)*u;
		d=v+1;
	}
	printf("%d\n",ret);
}
