import scala.io.StdIn.readLine

object Main {
  def main(args: Array[String]) {
    def printChessBoard: Unit ={
      val Array(a, b) = readLine().split(" ").map(_.toInt)
      if(a != 0 || b != 0) {
        for(j <- 0 until a) {
          var i = 0
          if(j % 2 == 0) {
            while (i < b) {
              if(i % 2 == 0) print("#") else print(".")
              i += 1
            }
          } else {
            while (i < b) {
              if(i % 2 == 0) print(".") else print("#")
              i += 1
            }
          }
          print("\n")
        }

        println()
        printChessBoard
      }
    }

    printChessBoard
  }
}