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 Fortran (gfortran v4.8.4) (judge verdict: Wrong Answer)

program arc102_a
    use,intrinsic :: iso_fortran_env
    implicit none
    integer(int32):: n,k,i
    integer(int32):: a0, ah
    read*, n,k
    a0=0
    ah=0

    do i=1,n
        if (mod(i,k)==0) a0=a0+1
    end do

    if (mod(k,2) == 0) then
        do i=1,n
            if (mod(i,k) == k/2) ah=ah+1
        end do
    end if

    print'(i0)', a0**3 + ah**3


end program arc102_a