import qualified Data.IntMap as I
import System.Random

main :: IO ()
main = do
  rd <- fmap (take 100000) rollIkasamaDice
  let im  = foldr (I.update ((Just $!) . succ)) im0 rd
      im0 = I.fromList $ zip [1..4] [0,0..]
  print im

rollIkasamaDice :: IO [Int]
rollIkasamaDice = do
  gen <- getStdGen
  let rs  = filter (/=0) $ map f $ randomRs (1, 16) gen
      f x | x > 4 = floor $ sqrt $ fromIntegral x
          | otherwise            = x
  return rs