class Start
  def main
    _ = input
    echo "? aa"
    while true
      x = readlines.gsub("\r", "").split("\n")
      break if x.size >= 2
      y = x[0]
      break if y.include?("!")
      echo "? #{y[-1]}a"
    end
  end

  protected

  def echo(*x)
    print(*x)
    puts
  end

  def input = gets.chomp
end

Start.new.main