Problem:
Score : 400 points

Problem Statement

Takahashi had a pair of two positive integers not exceeding N, (a,b), which he has forgotten.
He remembers that the remainder of a divided by b was greater than or equal to K.
Find the number of possible pairs that he may have had.

Constraints

1 \leq N \leq 10^5

0 \leq K \leq N-1

All input values are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the number of possible pairs that he may have had.

Sample Input 1

5 2

Sample Output 1

7

There are seven possible pairs: (2,3),(5,3),(2,4),(3,4),(2,5),(3,5) and (4,5).

Sample Input 2

10 0

Sample Output 2

100

Sample Input 3

31415 9265

Sample Output 3

287927211

Solution in C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
int main(void){
	int n,k,p,r;
	int a=0;
	scanf("%d",&n);
	scanf("%d",&k);
	for(int i=1;i<=n;i++){
		p=n/i;
		r=n-p*i;
		if(i>k){
			a+=(i-k)*p;
		}
		if(r>=k){
			a+=r-k+1;
		}
	}
	if(k!=0){
		printf("%d",a);
	}else{
		printf("%d",n*n);
	}
	return 0;
}