stringCircle :: String -> String
stringCircle str =
    unlines [[ maybe ' ' id $ lookup (x,y) ps | x <- [-2*ri..2*ri]] | y <- [-ri..ri]]
    where
      ri  = length str `div` 3
      ps  = zipWith f [0..] str
      f i c = ((round $ 2 * r * cos t, round $ r * sin t), c)
          where
            t = i / fromIntegral (length str) * 2 * pi - pi / 2
            r = fromIntegral ri :: Double

main :: IO ()
main = putStrLn $ stringCircle "子丑寅卯辰巳午未申酉戌亥"