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 Julia (0.5.0) (judge verdict: Time Limit Exceeded)

function main()
	n,k = parse.(split(readline()))
	count = 0
	q = div(2*n,k)
	for i in 1:q
		for j in 1:min(i*k-1,n)
			a = j
			b = k*i-j
			if b>0 && b<=n && a%k == b%k
				x = a%k
				if k-x <= n
					count += 1
					z = div(n-k+x,k)
					count += z
				end
			end
		end
	end
	print(count)
end
 
main()