import Control.Applicative
import Data.List



check :: Int -> Int -> [String]
check h w = [[(if (x+y)`mod`2==0 then '#' else '.') | x<-[1..w] ] | y<-[1..h] ]

main = do
{
    l <- map (map (read::String->Int) . words) . init . lines <$> getContents;
    let{
        sqs = [ check (x!!0) (x!!1)  | x<-l ];
    };
    mapM_ (mapM_ putStrLn) $ map (++[""]) sqs;
}