
wide = []
high = []
count = 0;

while wide[count - 1] != 0 && high[count - 1] != 0  do
	high[count],wide[count] = gets.split().map(&:to_i)
	count += 1 
end

for value in 0...count-1

	for countH in 0...high[value]

		for countW in 0...wide[value]
			case countH%2
			when 0
				if countW > 0 && countW%2 != 0 
					print '.'
				else 
					print '#'
				end
			else
				if countW > 0 && countW%2 != 0 
					print '#'
				else 
					print '.'
				end
			end
		end
		puts ""
	end
end