Problem:
Score : 300 points

Problem Statement

You are given integers N and K. Find the number of triples (a,b,c) of positive integers not greater than N such that a+b,b+c and c+a are all multiples of K.
The order of a,b,c does matter, and some of them can be the same.

Constraints

1 \leq N,K \leq 2\times 10^5

N and K are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the number of triples (a,b,c) of positive integers not greater than N such that a+b,b+c and c+a are all multiples of K.

Sample Input 1

3 2

Sample Output 1

9

(1,1,1),(1,1,3),(1,3,1),(1,3,3),(2,2,2),(3,1,1),(3,1,3),(3,3,1) and (3,3,3) satisfy the condition.

Sample Input 2

5 3

Sample Output 2

1

Sample Input 3

31415 9265

Sample Output 3

27

Sample Input 4

35897 932

Sample Output 4

114191

Solution in PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php 
 fscanf(STDIN, "%d %d", $N, $K);
$ans = 0 ;

 for($a = 0; $a < $N; $a++){
   for($b = 0; $b < $N ;$b++){
     for($s = 0; $s < $N*3; $s++){
     if($b!=$K*$s-$a) continue;
    for($c = 0; $c < $N ;$c++){

        if(($a+$b)%$K!=0) continue;
        if(($c+$b)%$K!=0) continue;
        if(($a+$c)%$K!=0) continue;

        $ans++;
    }
  }}
 }

echo $ans;
 ?>