import Control.Applicative
import Control.Monad

shapingData :: String -> [[Int]]
shapingData = map (map read . words) . takeWhile ( /= "0 0") . lines

evenLine :: Int -> String
evenLine a = take a startDotList
    where startDotList = concat $ repeat "#."

oddLine :: Int -> String
oddLine a = take a startSharpList
    where startSharpList = concat $ repeat ".#"

takeAlternately :: a -> a -> Int -> [a]
takeAlternately _ _' 0 = []
takeAlternately theOne theOther num = theOne : takeAlternately theOther theOne (num-1)


makeContents :: [Int] -> String
makeContents [a, b] = let evenLineNum = evenLine b
                          oddLineNum = oddLine b
                      in unlines $ takeAlternately evenLineNum oddLineNum a

main = do 
    line <- getContents
    mapM_ putStrLn (map makeContents (shapingData line))
