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 Go (1.6) (judge verdict: Time Limit Exceeded)

package main

import(
    "fmt"

)


func main (){
    var n, k , a, b, c, an  int
    fmt.Scan(&n,&k)
    for i:= 1 ; i <= n ; i++{
        for sec := 1 ; sec <=n ; sec++{
            for tre := 1 ; tre <= n ; tre++{
                a = i + sec
                b = i + tre
                c = sec + tre
                if a % k == 0 && b % k == 0 && c % k == 0{
                    an += 1
                }
            }
        }
    }
    fmt.Println(an)
}