data Color = White | Blue | Red | Green | Yellow deriving (Show, Eq)

next :: Color -> [Color]
next color = case color of
  White -> [Blue]
  Blue -> [White, Red]
  Red -> [Blue, Green]
  Green -> [Red, Yellow]
  Yellow -> [Green]

count :: [Color] -> Int -> Int
count col 1 = length col
count col n = count (col >>= next) (n-1)

main = mapM_ print $ map (count [White, Blue, Red, Green, Yellow]) [1..8]