def sharp(u,cnt)
  u.times{
    if cnt.even?
      print (".")
    else
      print ("#")
    end
    cnt += 1
  }
end

def f()
  h,w = gets.split.map(&:to_i)
  cnt=0
  return if h==0 && w==0
  h.times{
    if cnt.even?
      sharp(w,1)
    else
      sharp(w,0)
    end
    cnt+=1
    puts

  }
  puts
  f()
end

f()





