object Main extends App {
  def buildChessboard(w: Int, h: Int): String = {
    val chess = "#." * (w + h);
    (0 until h).map(x => chess.slice(x, x + w)).mkString("\n")
  }

  scala.io.Source.stdin.getLines.toList.init
    .map(_.split(" ").map(_.toInt))
    .map(x => buildChessboard(x(1), x(0)))
    .map(x => println(x + "\n"))
}