import scala.io.StdIn

object Main extends App {
  val inputs1 = StdIn.readLine().split(" ")
  val H = inputs1(0).toInt
  val W = inputs1(1).toInt
  val Ss: Seq[Seq[String]] = for(_ <- 1 to H) yield {StdIn.readLine().toCharArray.map(_.toString).toSeq}

  val flattenSs = Ss.flatten
  val areas =
    for {
      x <- 1 to W
      y <- 1 to H
    } yield {
      val hjamas = Ss.map(e => e(x))
      val height =
        hjamas.take(x - 1).reverse.takeWhile{e => e == "."}.size +
          hjamas.drop(x).takeWhile{e => e == "."}.size + 1

      val wjamas = Ss(y)
      val weight =
        wjamas.take(y - 1).reverse.takeWhile{e => e == "."}.size +
          wjamas.drop(y).takeWhile{e => e == "."}.size + 1

      height + weight - 1
    }

  println(areas.max)
}