In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
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Question: Passage: After the Nazis came to power, he emigrated to Switzerland in 1933 and to the United States later. He began his studies in Zurich and worked part-time as a house teacher. Meanwhile, he wrote articles and book reviews for the Neue Zürcher Zeitung, using several pseudonyms because of prohibition of work. He earned his PhD and taught French and German Literature at various universities, including Princeton University and University of Wisconsin-Madison. During a journey to Europe, Vordtriede was surprised by the outbreak of the Second World War and interned as an Enemy alien in occupied France. By interventions, he became free months later and was allowed to go back to America. He met his mother in New York City late in 1941, who also emigrated to the USA. He received the American citizenship in 1946 and became a Guggenheim Fellow in 1957. His sister Fränze emigrated in 1947 and went to Philadelphia.
 Link Information:  Zürich. The municipality has approximately 409,000 inhabitants, the urban agglomeration 1.315 million and the Zürich metropolitan area 1.83 million Answer: metropolitan area 1.83 million

Answer: What is the population of the city where Vordtriede once studied and worked as a teacher?


Question: Passage: John Silvester, the Recorder of London referenced the spectre of Napoleon Bonaparte and the burgeoning Napoleonic Wars in his announcement of Perring's appointment, stating that "At a time so awful as the present, when the country is threatened by an implacable and unprincipled enemy, it is of the last importance that the civic chair should be filled by a person in whom the greatest confidence can be placed". Silvester ominously warned Perring that "The keys of the Metropolis are placed in your hands, at the moment when the enemy are at the gates". The ball held later that day at Guildhall was opened with a minuet danced by Perring's eldest daughter and the Spanish Ambassador. The Napoleonic wars and the threat of a French invasion had led to coastal batteries being built as fortifications along the south coast of England in the summer of 1803. Perring was furious to find that a battery had been built on land that he owned at the mouth of the River Yealm in Devon, and wrote to the Secretary of War, Lord Hobart. Perring was eventually pacified by many letters from John Graves Simcoe, who was in charge of the construction of the defences. With the threat of invasion by the French still present, Perring presented the colours of the Corporation of London to the ten regiments of the London Loyal Infantry who assembled at Blackheath on 18 May 1804. Perring was accompanied on the grand procession to Blackheath by the Earl of Harrington, Earl Amherst and Prince Frederick, Duke of York.
 Link Information: Sir John Silvester, 1st Baronet (7 September 1745 – 30 March 1822) Answer: 24

Answer: What is the age difference between the Recorder of London who referenced Napoleon and Napoleon Bonaparte?


Question: Passage: On 17 April 2010, the president of German airline Air Berlin, in an interview with the newspaper Bild am Sonntag, stated that the risks for flights due to this volcanic haze were nonexistent, because the assessment was based only on a computer simulation produced by the VAAC. He went on to claim that the Luftfahrt-Bundesamt closed German airspace without checking the accuracy of these simulations. Spokesmen for Lufthansa and KLM stated that during their test flights, required by the European Union, there were no problems with the aircraft. On the morning of 17 April Lufthansa moved 10 aircraft from Munich to Frankfurt at low altitude following visual flight rules. There were no problems reported and no sign of damage to the planes. The same day, an Airbus belonging to Ural Airlines attempted flying below the ash clouds from Moscow to Rimini. When the airplane was in Austrian airspace, the crew reported being low on fuel and diverted to Vienna, where the airplane landed safely.
 Link Information: On 17 April 2010, the president of German airline Air Berlin, in an interview with the newspaper Bild am Sonntag, stated that the risks for flights due to this volcanic haze were nonexistent Answer: 3548000

Answer:
How many subscribers did the newspaper Bild am Sonntag have the year that the president of German airline Air Berlin, in an interview with the newspaper stated that the risks for flights due to this volcanic haze were nonexistent?