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: What needs consistency?, Context: The simplest valve gears give events of fixed length during the engine cycle and often make the engine rotate in only one direction. Most however have a reversing mechanism which additionally can provide means for saving steam as speed and momentum are gained by gradually "shortening the cutoff" or rather, shortening the admission event; this in turn proportionately lengthens the expansion period. However, as one and the same valve usually controls both steam flows, a short cutoff at admission adversely affects the exhaust and compression periods which should ideally always be kept fairly constant; if the exhaust event is too brief, the totality of the exhaust steam cannot evacuate the cylinder, choking it and giving excessive compression ("kick back").[citation needed]
Example Output: exhaust and compression periods

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: Who was the leader hoping to get along with?, Context: President Franklin D. Roosevelt promoted a "good neighbor" policy that sought better relations with Mexico. In 1935 a federal judge ruled that three Mexican immigrants were ineligible for citizenship because they were not white, as required by federal law. Mexico protested, and Roosevelt decided to circumvent the decision and make sure the federal government treated Hispanics as white. The State Department, the Census Bureau, the Labor Department, and other government agencies therefore made sure to uniformly classify people of Mexican descent as white. This policy encouraged the League of United Latin American Citizens in its quest to minimize discrimination by asserting their whiteness.
Example Output:
Mexico