import Control.Applicative
import Data.List

ints :: String -> [Int]
ints s = map read $ words s

getLines :: IO [[Int]]
getLines = do
  [a, b] <- ints <$> getLine
  if a == 0 && b == 0
    then return []
    else do
      rest <- getLines
      return ([a, b] : rest)

calc :: Int -> Int -> String
calc w h = intercalate "\n" $ c
  where
    a = take w $ cycle "#."
    b = take w $ cycle ".#"
    c = take h $ cycle [a, b]

main :: IO ()
main = do
  xs <- getLines
  putStrLn $ intercalate "\n\n" [calc w h | ys <- xs, let [h, w] = ys]
  putStrLn ""