while line = gets
  h, w = line.split(' ').map(&:to_i)
  odd = (w / 2)times..map{"#."}.join
  odd = odd + "#" if w.odd?
  even = (w / 2).times.map{".#"}.join
  even = even + "#" if w.odd?
  (h / 2).times.each do
    puts odd
    puts even
  end
  puts odd if h.odd?
  puts
end
