import Control.Applicative
import Data.Function
import Control.Monad

makeEvenLine w =  take w $ concat $ zipWith (\a b -> [a,b]) (repeat '#') (repeat '.')
makeOddLine w =  tail $ makeEvenLine $ w+1
makeSq h w = take h $ concat $ repeat [makeEvenLine w, makeOddLine w]

main :: IO ()
main = fix $ \loop -> do
    [h,w] <- map read . words <$> getLine
    unless (h == 0) $ do
        forM_ (makeSq h w) $ \l -> putStrLn l
        putStrLn ""
        loop
