main :: IO ()
main = readLn >>= putStr . unlines . sierpinski 32 63

sierpinski :: Int -> Int -> Int -> [String]
sierpinski _ m 0 = f <$> [1,3..m]
  where
    f i = zeroes ++ (replicate i '1') ++ zeroes
      where zeroes = replicate ((m - i) `div` 2) '_'

sierpinski n m i = (zeroes `comb` smaller `comb` zeroes)
  ++ (smaller `comb` column `comb` smaller)
  where
    m' = m `div` 2
    n' = n `div` 2
    smaller = sierpinski n' m' (i - 1)
    zeroes = replicate n' $ replicate ((m - m') `div` 2) '_'
    column = replicate n' "_"
    comb = zipWith (++)