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 (GNU Fortran 9.2.1) (judge verdict: Runtime Error)

program prob2
    implicit none
    integer::x1, x2, x3, x4, y1, y2, y3, y4, dx, dy
    read(*,*) x1, y1, x2, y2
    dx = x2 - x1
    dy = y2 - y1
    if(dx >= 0 .and. dy >= 0) then !-+
        x3 = x2 - dy
        y3 = y2 + dx
    else if(dx >= 0 .and. dy <= 0) then !++
        x3 = x2 - dy
        y3 = y2 + dx
    else if(dx <= 0 .and. dy >= 0) then !--
        x3 = x2 - dy
        y3 = y2 + dx
    else if(dx <= 0 .and. dy <= 0) then !+-
        x3 = x2 - y2
        y3 = y2 + x2
    end if
    x4 = x3 - dx
    y4 = y3 - dy
    write(*,*) x3, y3, x4, y4
    stop
end program