import scala.io.StdIn._
object Main extends App {
  val Array(height, width) = readLine.trim.split(' ').map(_.toInt)
  val state = Array.fill(height){readLine.trim}
  val up = Array.fill(height){Array.fill(width){0}}
  val down = Array.fill(height){Array.fill(width){0}}
  val left = Array.fill(height){Array.fill(width){0}}
  val right = Array.fill(height){Array.fill(width){0}}
  for (w ← 0 until width if state(0)(w) == '.') up(0)(w) = 1
  for (w ← 0 until width if state(height - 1)(w) == '.') down(height - 1)(w) = 1
  for (h ← 0 until height if state(h)(0) == '.') left(h)(0) = 1
  for (h ← 0 until height if state(h)(width - 1) == '.') right(h)(width - 1) = 1
  for {h ← 1 until height
       w ← 0 until width} {
    if (state(h)(w) == '.') {
      up(h)(w) = up(h - 1)(w) + 1
    }
    if (state(height - h - 1)(w) == '.') {
      down(height - h - 1)(w) = down(height - h)(w) + 1
    }
  }
  for {h ← 0 until height
       w ← 1 until width} {
    if (state(h)(w) == '.') {
      left(h)(w) = left(h)(w - 1) + 1
    }
    if (state(h)(width - w - 1) == '.') {
      right(h)(width - w - 1) = right(h)(width - w) + 1
    }
  }
  println(
    (0 until height).flatMap(h ⇒ (0 until width).map(w ⇒ up(h)(w) + down(h)(w) + left(h)(w) + right(h)(w) - 3)).max
  )
}
