Input: Read this: The fighter aircraft of the USAF are small, fast, and maneuverable military aircraft primarily used for air-to-air combat. Many of these fighters have secondary ground-attack capabilities, and some are dual-roled as fighter-bombers (e.g., the F-16 Fighting Falcon); the term "fighter" is also sometimes used colloquially for dedicated ground-attack aircraft. Other missions include interception of bombers and other fighters, reconnaissance, and patrol. The F-16 is currently used by the USAF Air Demonstration squadron, the Thunderbirds, while a small number of both man-rated and non-man-rated F-4 Phantom II are retained as QF-4 aircraft for use as Full Scale Aerial Targets (FSAT) or as part of the USAF Heritage Flight program. These extant QF-4 aircraft are being replaced in the FSAT role by early model F-16 aircraft converted to QF-16 configuration. The USAF has 2,025 fighters in service as of September 2012.
Question: What are the QF-4 aircraft being replaced by the US Air Force?

Output: early model F-16 aircraft converted to QF-16 configuration

Input: Read this: During the period between 1582, when the first countries adopted the Gregorian calendar, and 1923, when the last European country adopted it, it was often necessary to indicate the date of some event in both the Julian calendar and in the Gregorian calendar, for example, "10/21 February 1750/51", where the dual year accounts for some countries already beginning their numbered year on 1 January while others were still using some other date. Even before 1582, the year sometimes had to be double dated because of the different beginnings of the year in various countries. Woolley, writing in his biography of John Dee (15271608/9), notes that immediately after 1582 English letter writers "customarily" used "two dates" on their letters, one OS and one NS.
Question: What happened in the fifteenth century that made it necessary to give dates using both calendars?

Output: unanswerable

Input: Read this: The 1981 film Fort Apache, The Bronx is another film that used the Bronx's gritty image for its storyline. The movie's title is from the nickname for the 41st Police Precinct in the South Bronx which was nicknamed "Fort Apache". Also from 1981 is the horror film Wolfen making use of the rubble of the Bronx as a home for werewolf type creatures. Knights of the South Bronx, a true story of a teacher who worked with disadvantaged children, is another film also set in the Bronx released in 2005. The Bronx was the setting for the 1983 film Fuga dal Bronx, also known as Bronx Warriors 2 and Escape 2000, an Italian B-movie best known for its appearance on the television series Mystery Science Theatre 3000. The plot revolves around a sinister construction corporation's plans to depopulate, destroy and redevelop the Bronx, and a band of rebels who are out to expose the corporation's murderous ways and save their homes. The film is memorable for its almost incessant use of the phrase, "Leave the Bronx!" Many of the movie's scenes were filmed in Queens, substituting as the Bronx. Rumble in the Bronx was a 1995 Jackie Chan kung-fu film, another which popularised the Bronx to international audiences. Last Bronx, a 1996 Sega game played on the bad reputation of the Bronx to lend its name to an alternate version of post-Japanese bubble Tokyo, where crime and gang warfare is rampant.
Question: When was 'Fuga dal Bronx' released?

Output: 2005

Input: Read this: Edwin Chadwick's 1829 article, "Preventive police" in the London Review, argued that prevention ought to be the primary concern of a police body, which was not the case in practice. The reason, argued Chadwick, was that "A preventive police would act more immediately by placing difficulties in obtaining the objects of temptation." In contrast to a deterrent of punishment, a preventive police force would deter criminality by making crime cost-ineffective - "crime doesn't pay". In the second draft of his 1829 Police Act, the "object" of the new Metropolitan Police, was changed by Robert Peel to the "principal object," which was the "prevention of crime." Later historians would attribute the perception of England's "appearance of orderliness and love of public order" to the preventive principle entrenched in Peel's police system.
Question: When was 'Preventive Police' not published?

Output:
unanswerable