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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        String[] line = br.readLine().split(" ");
        int N = Integer.parseInt(line[0]);
        int K = Integer.parseInt(line[1]);

        int multipleOfK = N / K;
        int multipleOfHalfOfK = 0;

        if (K % 2 == 1) {
            out.println((int)Math.pow(multipleOfK, 3));
        } else {
            if (multipleOfK + K / 2 <= K) {
                multipleOfHalfOfK = multipleOfK + 1;
            } else {
                multipleOfHalfOfK = multipleOfK;
            }
            out.println((int)(Math.pow(multipleOfK, 3) + Math.pow(multipleOfHalfOfK, 3)));
        }
        out.close();
    }
}