h,w = gets.chomp.split(" ").map(&:to_i)
s = Array.new.map{Array.new}
h.times do |i|
  s[i] = gets.chomp
end
left = Array.new(h).map{Array.new(w,0)}
right = Array.new(h).map{Array.new(w,0)}
up = Array.new(h).map{Array.new(w,0)}
down = Array.new(h).map{Array.new(w,0)}
for i in 0..h-1
  for j in 0..w-1
    if s[i][j] == '#'
      left[i][j] = 0
    elsif j == 0
      left[i][j] = 1
    else
      left[i][j] = left[i][j-1] + 1
    end
  end
end
for i in 0..h-1
  for j in 0..w-1
    if s[i][w-1-j] == '#'
      right[i][w-1-j] = 0
    elsif j == 0
      right[i][w-1-j] = 1
    else
      right[i][w-1-j] = right[i][w-1-j+1] + 1
    end
  end
end
for j in 0..w-1
  for i in 0..h-1
    if s[i][j] == '#'
      down[i][j] = 0
    elsif i == 0
      down[i][j] = 1
    else
      down[i][j] = down[i-1][j] + 1
    end
  end
end
for j in 0..w-1
  for i in 0..h-1
    if s[h-1-i][j] == '#'
      up[h-1-i][j] = 0
    elsif i == 0
      up[h-1-i][j] = 1
    else
      up[h-1-i][j] = up[h-1-i+1][j] + 1
    end
  end
end
max = 0
for i in 0..h-1
  for j in 0..w-1
    max = [max,left[i][j] + right[i][j] + up[i][j] + down[i][j] - 3].max
  end
end
puts max