H, W = gets.split().map(&:to_i)
right = Array.new(H) { Array.new(W, 0) }
left  = Array.new(H) { Array.new(W, 0) }
up    = Array.new(H) { Array.new(W, 0) }
down  = Array.new(H) { Array.new(W, 0) }
map = []
#mapの取得
H.times do |h|
  map[h] = gets.chomp
end

#R, L, U, D の４回
#R
H.times do |h|
  W.times do |w|
    if map[h][w] ==  '#'
      right[h][w] = 0
    elsif map[h][w] ==  '.' && w == 0
      right[h][w] = 1
    else
      right[h][w] = right[h][w-1] + 1 
    end
  end
end

#R
H.times do |h|
  W.times do |w|
    if map[h][W-w-1] ==  '#'
      left[h][W-w-1] = 0
    elsif map[h][W-w-1] ==  '.' && w == 0
      left[h][W-w-1] = 1
    else
      left[h][W-w-1] = left[h][W-w] + 1 
    end
  end
end

#U
W.times do |w|
  H.times do |h|
    if map[h][w] ==  '#'
      up[h][w] = 0
    elsif map[h][w] ==  '.' && h == 0
      up[h][w] = 1
    else
      up[h][w] = up[h-1][w] + 1 
    end
  end
end

#D
W.times do |w|
  H.times do |h|
    if map[H-h-1][w] ==  '#'
      down[H-h-1][w] = 0
    elsif map[H-h-1][w] ==  '.' && h == 0
      down[H-h-1][w] = 1
    else
      down[H-h-1][w] = down[H-h][w] + 1 
    end
  end
end


##SUM!

H.times do |h|
  W.times do |w|
    right[h][w] += left[h][w] + up[h][w] + down[h][w] - 3
  end
end
puts right.flatten.max