main = 
  let 
    func = do
      line <- getLine
      let 
        [h,w] = map read $ words line :: [Int]
        drawOddLine x 
          | x == (w+1)      = do
            putStrLn ""
          | (mod x 2) == 0  = do
            putStr "."
            drawOddLine (x+1)
          | (mod x 2) == 1  = do
            putStr "#"
            drawOddLine (x+1)
        drawEvenLine x 
          | x == (w+1)      = do
            putStrLn ""
          | (mod x 2) == 0  = do
            putStr "#"
            drawEvenLine (x+1)
          | (mod x 2) == 1  = do
            putStr "."
            drawEvenLine (x+1)
        drawBoard y
          | y == (h+1)      = do
            putStrLn ""
          | (mod y 2) == 0  = do
            drawEvenLine 1
            drawBoard (y+1)
          | (mod y 2) == 1  = do
            drawOddLine 1
            drawBoard (y+1)
        in 
          if h == 0 && w == 0
            then putStr ""
            else do
              drawBoard 1 
              func
    in func

