T = gets.to_i

def send_query(y)
  STDOUT.puts("? %.12f" % y)
  STDOUT.flush

  res = gets.chomp
  res == "Yes"
end

T.times do
  ok = 0.000001
  ng = 12.22 * 10 ** 74 + 1.0

  24.times do
    y = Math.sqrt(ok * ng)

    if send_query(y)
      ok = y
    else
      ng = y
    end
  end

  STDOUT.puts("! %.12f" % Rational(2 * ok * ng, ok + ng))
  STDOUT.flush
end