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;
int k;
int main(){
	scanf("%d",&n);
	for(int i=1;i<n;++i){
		for(int j=1;i*j<n;++j){
			++k;
		}
	}
	printf("%d\n",k);
	return 0;
}
