In this task, you are given a question and a context passage. You have to answer the question based on the given passage.

Example Input: Who ruled Bithynia before Bas?, Context: The Bithynians were a Thracian people living in northwest Anatolia. After Alexander's conquests the region of Bithynia came under the rule of the native king Bas, who defeated Calas, a general of Alexander the Great, and maintained the independence of Bithynia. His son, Zipoetes I of Bithynia maintained this autonomy against Lysimachus and Seleucus I, and assumed the title of king (basileus) in 297 BCE. His son and successor, Nicomedes I, founded Nicomedia, which soon rose to great prosperity, and during his long reign (c. 278 c. 255 BCE), as well as those of his successors, the kingdom of Bithynia held a considerable place among the minor monarchies of Anatolia. Nicomedes also invited the Celtic Galatians into Anatolia as mercenaries, and they later turned on his son Prusias I, who defeated them in battle. Their last king, Nicomedes IV, was unable to maintain himself against Mithridates VI of Pontus, and, after being restored to his throne by the Roman Senate, he bequeathed his kingdom by will to the Roman republic (74 BCE).
Example Output: Calas

Example Input: What type of equipment is used with liquid oxygen but not other methods of oxygen storage?, Context: Oxygen storage methods include high pressure oxygen tanks, cryogenics and chemical compounds. For reasons of economy, oxygen is often transported in bulk as a liquid in specially insulated tankers, since one liter of liquefied oxygen is equivalent to 840 liters of gaseous oxygen at atmospheric pressure and 20 C (68 F). Such tankers are used to refill bulk liquid oxygen storage containers, which stand outside hospitals and other institutions with a need for large volumes of pure oxygen gas. Liquid oxygen is passed through heat exchangers, which convert the cryogenic liquid into gas before it enters the building. Oxygen is also stored and shipped in smaller cylinders containing the compressed gas; a form that is useful in certain portable medical applications and oxy-fuel welding and cutting.
Example Output: heat exchangers

Example Input: When did he pass away, in relation to his trip to Beijing?, Context: Chen states that the fourth Dalai Lama Yonten Gyatso was granted the title "Master of Vajradhara" and an official seal by the Wanli Emperor in 1616. This was noted in the Biography of the Fourth Dalai Lama, which stated that one Soinam Lozui delivered the seal of the Emperor to the Dalai Lama. The Wanli Emperor had invited Yonten Gyatso to Beijing in 1616, but just like his predecessor he died before being able to make the journey.
Example Output:
before