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.util.Scanner;

public class Main {
	public static void main(String[] args) {
	
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int K = scan.nextInt();
		
		if (N<=0 || K<0 || K>2*Math.pow(10,5)){
			System.out.println("error");
		}
		else
		{
			if(K%2==1){
				int count = 0;
				for(int i = 1 ; i<=N;i++){
					if(i%K == K/2){
						count++;
					}
				}
				
				System.out.println(count);
			}
			else{
				int count = 0;
				for(int i = 1 ; i<=N;i++){
					if(i%K == 0){
						count++;
					}
				}	
				
				System.out.println(count);
			}
			
		}
		
	}

}