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: Runtime Error)

import java.util.*;
public class Main{
	public static void main(String[] args) {
		Scanner Xu=new Scanner(System.in);
		int N=Xu.nextInt();
		int k=Xu.nextInt();
		Xu.close(); 
		long num=0;
		long[] a = new long[10010];
		int r=N%k;
			for(int i=1;i<=k;i++)
			   {
					a[i]=N/k;
			   }
		    for(int i=1;i<=r;i++) a[i]++;
		    num+=a[k]*a[k]*a[k];
		    if(k%2==0)
		    	num+=a[k/2]*a[k/2]*a[k/2];
		    System.out.println(num);
		}
	}