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: Time Limit Exceeded)

#include<stdio.h>
int main(void) {
	unsigned long n, k, i, j,h;
	unsigned long cont = 0;
	scanf("%lu%lu", &n, &k);
	for (i = 1; i <= n; i++) {
               h = 0;
		for (j = 1; j <= n; j++) {
			if (k <= (i % j)) {
                                 if(h == 0)h = 1;
				cont += 1;
			}
                       else if(k <= (i % j) && h == 1)break;
		}
	}
	printf("%lu", cont);
	return 0;
}