f = true;
e = false;
 
while (s = gets) && !e do
  if f then
    f = false;
  else
    puts;
  end
  a = s.split(" ").map(&:to_i);
  s1 = ("#." * (a[1] / 2)) + (a[1].even? ? "" : "#");
  s2 = (".#" * (a[1] / 2)) + (a[1].even? ? "" : ".");
  a[0].times{|i|
    if i.even? then
      puts s1;
    else
      puts s2;
    end
  }
end