loop do
    h, w = gets.split.map(&:to_i)
    break if h == 0
    input = (1..h).map { gets.chomp.split("") }
    next_mark_pos = Array.new(h).map { Array.new(w) }

    (0..h-1).each do |i|
        (w-1).downto(0) do |j|
            if input[i][j] == ?*
                next_mark_pos[i][j] = j
            elsif j == w - 1
                next_mark_pos[i][j] = w
            else
                next_mark_pos[i][j] = next_mark_pos[i][j+1]
            end
        end
    end

    m = 0

    (0..h-1).each do |i|
        (0..w-1).each do |j|
            next if input[i][j] == ?*
            l = w - 1
            (i..h-1).each do |k|
                l = [l, next_mark_pos[k][j] - 1].min
                break if l <= j
                s = (k - i + 1) * (l - j + 1)
                m = s if s > m
            end
        end
    end

    p m
end

