inputs = []
while str = STDIN.gets
  if str.chomp == "0 0" then break end
  inputs << str.chomp
end

def describe_rectangle(h, w)
  # puts "h = #{h}, w = #{w}"
  output = ""
  for j in 1..h do
    for i in 1..w do
      if j % 2 == 1 then
        if i % 2 == 1 then
          output += "#"
        else
          output += "."
        end
      else
        if i % 2 == 1 then
          output += "."
        else
          output += "#"
        end
      end
    end
    output += "\n"
  end
  puts output
end

# puts inputs
for num in 0..inputs.length - 1 do
  rec = inputs[num].split(" ")
  # puts "rec = #{rec}"
  describe_rectangle(rec[0].to_i, rec[1].to_i)
  puts "\n"
end