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 PHP (5.6.30) (judge verdict: Time Limit Exceeded)

<?php
# 整数の入力
$a = fgets(STDIN);

$e = explode(" ",$a);
$n = $e[0];
$k = $e[1];

for ($j = 1 ; $j <= $n ;$j++){
for ($i = 1 ; $i <= $n ;$i++){
if ($i % $j >= $k){
  $ans++;
}
}
}
echo $ans;

?>