import Control.Applicative

main = do
    ss <- words <$>getLine
    let h:w:_ = [read x| x<- ss] ::[Int]
    if h==0 then return ()
    else do
      let o = concat[ [if even (x+y) then '#' else '.'|x <- [0..w-1] ] ++"\n"| y<- [0..h-1]]
      putStrLn $ o
      main