H, W = gets.chomp.split(" ").map(&:to_i)

dungeon = []

H.times{ |i|
  s = gets.chomp.split("")
  dungeon.push(s)
}

ans = 0

def search_ver(x, y, dungeon)
  tmp = 0
  i = x
  while i >= 0 && dungeon[i][y] == "."  do
    i -= 1
    tmp += 1
  end
  i = x
  while i <= H-1 && dungeon[i][y] == "." do
    i += 1
    tmp += 1
  end
  # p "|"
  # p
  tmp = tmp - 1
end

def search_hol(x, y, dungeon)
  tmp = 0
  i = y
  while i >= 0 && dungeon[x][i] == "." do
    i -= 1
    tmp += 1
  end
  i = y
  while i <= W-1 && dungeon[x][i] == "." do
    i += 1
    tmp += 1
  end
  # p "-"
  # p
  tmp = tmp - 1
end

ans = 0

H.times{ |i|
  W.times{|j|
    if dungeon[i][j] == "." then
      ans = [search_hol(i, j, dungeon) + search_ver(i, j, dungeon) - 1, ans].max
    end
  }
}

puts ans
