import Data.Functor( (<$>))

main = do
    ls <- (takeWhile ("0 0"/=)) . lines <$> getContents
    let
	hws = (read <$>) . words <$> ls
	printRect [h,w] = putStrLn `mapM_` rect >> putStrLn ""
	  where
	    l1 = take w $ cycle "#."
	    l2 = take w $ cycle ".#"
	    rect = take h $ cycle [l1,l2]

    printRect `mapM_` hws


