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 C (Clang 3.8.0) (judge verdict: Time Limit Exceeded)

//ABC001C
#include <stdio.h>
int main(){
	int N, K;
	scanf("%d %d",&N,&K);
	int a, b, c;
	int count=0;
	for(a=1;a<=N;a++){
		for(b=1;b<=N;b++){
			for(c=1;c<=N;c++){
				if((a+b)%K==0 & (b+c)%K==0 & (c+a)%K==0){
					count++;
				}
			}
		}
	}
	printf("%d",count);
}