while true do
	h,w = gets.split.map(&:to_i)
	if h == 0 && w == 0
		break
	end
	i = 0
	while i < h do
		r = ""
		if i % 2 == 0 or i == 0
			for num in 1..w do
				if num == 1 or num % 2 == 1 
					r = r + "#" 
				else
					r = r + "." 
				end
			end
		else
			for num in 1..w do
				if num == 0 or num % 2 == 0 
					r = r + "#" 
				else
					r = r + "." 
				end
			end
		end
	puts r
	i = i + 1
	end

	puts ""
end
