class Interactive
  def solve_exp
    if query(1)
      return -1
    end

    ok = 76
    ng = -1
    while (ok - ng).abs > 1
      mid = (ok + ng) / 2
      if query(10 ** mid)
        ok = mid
      else
        ng = mid
      end
    end
    ok
  end

  def solve
    exp = solve_exp

    ok = 1.0
    ng = 0
    while (ok - ng).abs > 0.00001
      mid = (ok + ng) / 2
      if query(mid * (10 ** exp))
        ok = mid
      else
        ng = mid
      end
    end

    ok * (10 ** exp)
  end

  def query(v)
    send_query(v)
    read
  end

  def send_query(v)
    @sent_query = v

    $stdout.puts "? %.10f" % v
    $stdout.flush
  end

  def read
    case $stdin.gets.chomp
    when /y/i
      true
    when /n/i
      false
    else
      raise
    end
  end
end

gets.to_i.times do
  ans = Interactive.new.solve
  $stdout.puts "! %.10f" % ans
  $stdout.flush
end