main = do
    str <- getLine
    let [h, w] = map read $ words $ str :: [Int]
    if h == 0 && w == 0
        then return ()
        else do
            let list = [if even x then "#" else "." | x <- [0..w]]
            putStrLn . unlines $ [if even y then concat $ init list else concat $ tail list | y <- [0..h-1]]
            main