Input: Read this: The last opus number that Chopin himself used was 65, allocated to the Cello Sonata in G minor. He expressed a deathbed wish that all his unpublished manuscripts be destroyed. At the request of the composer's mother and sisters, however, his musical executor Julian Fontana selected 23 unpublished piano pieces and grouped them into eight further opus numbers (Opp. 6673), published in 1855. In 1857, 17 Polish songs that Chopin wrote at various stages of his life were collected and published as Op. 74, though their order within the opus did not reflect the order of composition.
Question: When was Op. 74 published?

Output: 1857

Input: Read this: Voyager 2 is the only spacecraft that has visited Neptune. The spacecraft's closest approach to the planet occurred on 25 August 1989. Because this was the last major planet the spacecraft could visit, it was decided to make a close flyby of the moon Triton, regardless of the consequences to the trajectory, similarly to what was done for Voyager 1's encounter with Saturn and its moon Titan. The images relayed back to Earth from Voyager 2 became the basis of a 1989 PBS all-night program, Neptune All Night.
Question: When did a spacecraft get closest to Neptune?

Output: 25 August 1989

Input: Read this: Reaction to the novel varied widely upon publication. Literary analysis of it is sparse, considering the number of copies sold and its widespread use in education. Author Mary McDonough Murphy, who collected individual impressions of To Kill a Mockingbird by several authors and public figures, calls the book, "an astonishing phenomenon". In 2006, British librarians ranked the book ahead of the Bible as one "every adult should read before they die". It was adapted into an Oscar-winning film in 1962 by director Robert Mulligan, with a screenplay by Horton Foote. Since 1990, a play based on the novel has been performed annually in Harper Lee's hometown of Monroeville, Alabama.
Question: British librarians in 2006 ranked the book ahead of what famous volume?

Output: Bible

Input: Read this: Brass, which is an alloy of copper and zinc, has been used since at least the 10th century BC in Judea and by the 7th century BC in Ancient Greece. Zinc metal was not produced on a large scale until the 12th century in India and was unknown to Europe until the end of the 16th century. The mines of Rajasthan have given definite evidence of zinc production going back to the 6th century BC. To date, the oldest evidence of pure zinc comes from Zawar, in Rajasthan, as early as the 9th century AD when a distillation process was employed to make pure zinc. Alchemists burned zinc in air to form what they called "philosopher's wool" or "white snow".
Question: When was zinc introduced to Europe?

Output:
end of the 16th century