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 JavaScript (node.js v5.12) (judge verdict: Accepted)

'use strict';

function Main(input) {
  const N = Number(input.split(' ')[0]);
  const K = Number(input.split(' ')[1]);

  if(K % 2 !== 0) {
    console.log(Math.pow(Math.floor(N/K), 3));
  } else {
    if(N*2 >= ((Math.floor(N/K) * 2)+1)*K ) {
      console.log(Math.pow(Math.floor(N/K), 3) + Math.pow(Math.floor(N/K)+1, 3));
    } else {
      console.log(Math.pow(Math.floor(N/K), 3) + Math.pow(Math.floor(N/K), 3));
    }
  }




};
Main(require("fs").readFileSync("/dev/stdin", "utf8").trim());