import Control.Applicative

main :: IO ()
main = do
  [x, y] <- map read . words <$> getLine
  if (x, y) /= (0, 0)
  then printBoard x y
  else return ()
  where printBoard x y = unlines [if (i `mod` 2) == 1 then [if (a `mod` 2) == 1 then '#' else '.' | a <- [1..y]] else [if (b `mod` 2) == 0 then '#' else '.' | b <- [1..y]] | i <- [1..x]]
  
