h, w = gets.split.map(&:to_i)
s = h.times.map { gets.chomp.chars }

l = Array.new(h) { Array.new(w, 0) }
r = Array.new(h) { Array.new(w, 0) }
d = Array.new(h) { Array.new(w, 0) }
u = Array.new(h) { Array.new(w, 0) }

(0..h-1).each do |i|
  (0..w-1).each do |j|

    if i == 0
      u[i][j] = 1
      d[h-1][j] = 1
    else
      u[i][j] = u[i-1][j] + 1
      d[h-1-i][j] = d[h-i][j] + 1
    end

    if j == 0
      l[i][j] = 1
      r[i][w-1] = 1
    else
      l[i][j] = l[i][j-1] + 1
      r[i][w-1-j] = r[i][w-j] + 1
    end

    if s[i][j] == "#"
      l[i][j] = 0
      d[i][j] = 0
    end

    if s[h-1-i][j] == "#"
      u[h-1-i][j] = 0
    end

    if s[i][w-1-j] == "#"
      r[i][w-1-j] = 0
    end
  end
end

ans = 0
(0..h-1).each do |i|
  (0..w-1).each do |j|
    ans = [ans, l[i][j] + r[i][j] + d[i][j] + u[i][j] - 3].max
  end
end
puts ans
