Given the task definition, example input & output, solve the new input case.
In this task, you're given a question, along with three passages, 1, 2, and 3. Your job is to determine which passage can be used to answer the question by searching for further information using terms from the passage. Indicate your choice as 1, 2, or 3.
Example: Question: When did the operation during which the 704th dropped supplies to allied troops near Nijmegen begin? Passage 1: The group was occasionally diverted from strategic missions to carry out air support and interdiction missions. It supported Operation Overlord, the invasion of Normandy by attacking transportation targets, including bridges, along with airfields and strong points in France. On D Day, the squadron and the rest of the 446th Group led the first heavy bomber mission of the day. The 446th aided ground forces at Caen and Saint-Lô during July by hitting bridges, gun batteries, and enemy troops. During Operation Market Garden, the attempt to seize a bridgehead across the Rhine in the Netherlands, the 704th dropped supplies to allied troops near Nijmegen. It struck lines of communications during the Battle of the Bulge. During Operation Varsity in March 1945, it supplied ground and airborne troops near Wesel. The squadron flew its last combat mission on 25 April 1945 against Salzburg, Austria. The group had flown 273 missions and had lost 58 aircraft during the war,
. Passage 2: John Ford (1894–1973) was an American film director whose career spanned from 1913 to 1971. During this time he directed more than 140 films. Born in Maine, Ford entered the filmmaking industry shortly after graduating from high school with the help of his older brother, Francis Ford, who had established himself as a leading man and director for Universal Studios. After working as an actor, assistant director, stuntman, and prop man – often for his brother – Universal gave Ford the opportunity to direct in 1917. Initially working in short films, he quickly moved into features, largely with Harry Carey as his star. In 1920 Ford left Universal and began working for the Fox Film Corporation. During the next ten years he directed more than 30 films, including the westerns The Iron Horse (1924) and 3 Bad Men (1926), both starring George O'Brien, the war drama Four Sons and the Irish romantic drama Hangman's House (both 1928 and both starring Victor McLaglen). In the same year of these last two films, Ford directed his first all-talking film, the short Napoleon's Barber. The following year he directed his first all-talking feature, The Black Watch.
. Passage 3: Since the late 1970s, the central part of NYU is its Washington Square campus in the heart of Greenwich Village. Despite being public property, and expanding the Fifth Avenue axis into Washington Square Park, the Washington Square Arch is the unofficial symbol of NYU. Until 2008, NYU's commencement ceremony was held in Washington Square Park. However, due to space constraints, ceremonies are now held at the Yankee Stadium. Important facilities at Washington Square are the Elmer Holmes Bobst Library, designed by Philip Johnson and Richard Foster, who also designed several other structures, such as Tisch Hall, Meyer Hall, and the Hagop Kevorkian Center. When designing these buildings Johnson and Foster also set up a master plan for a complete redesign of the NYU Washington Square campus. However, it was never implemented. Other historic buildings include the Silver Center (formerly known as "Main building"); the Brown Building of Science; Judson Hall, which houses the King Juan Carlos I of Spain Center; Vanderbilt Hall, the historic townhouse row on Washington Square North; The Grey Art Gallery at 100 Washington Square East, housing the New York University art collection and featuring museum quality exhibitions; the Kaufman Management Center; and the Torch Club – the NYU dining and club facility for alumni, faculty, and administrators. Just a block south of Washington Square is NYU's Washington Square Village, housing graduate students and junior and senior faculty residences in the Silver Towers, designed by I. M. Pei, where an enlargement of Picasso's sculpture Bust of Sylvette (1934) is displayed.
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Output: 1
The question refers to the 704th unit and task about war which is decribed by Passage 1.

New input case for you: Question: How many miles long is the river that Silvanus drove the Alamanni tribesmen back from? Passage 1:Like the star Epsilon Draconis in the constellation of Draco, Beta Cephei is visible primarily in the northern hemisphere, given its extreme northern declination of 70 degrees and 34 minutes. It is nevertheless visible to most observers throughout the world reaching as far south as cities like Harare in Zimbabwe, Santa Cruz de la Sierra in Bolivia or other settlements north ± 19° South latitude. It is circumpolar throughout all of Europe, northern Asia, and North American cities as far south as Guadalajara in west central Mexico. All other locations around the globe having a latitude greater than ± 20° North will notice that the star is always visible in the night sky. Because Beta Cephei is a faint third magnitude star, it may be difficult to identify in most light polluted cities, though in rural locations the star should be easily observable.
 Passage 2:After the outbreak of the Great War, Thommée joined the 276th Infantry Regiment and served with distinction as a commanding officer of a company and then battalion. In 1916 he was promoted to the rank of lieutenant colonel and became an adjutant at the staff of the 48th Corps in the area of the Romanian front. After the Russian Revolution of 1917, he quit the army and on 25 September 1918 he joined the Polish Army in the area of Kuban. There, on 9 November he became the de facto chief of staff of Lucjan Żeligowski's Polish 4th Rifle Division, formally a part of the Polish Blue Army allied to France, United Kingdom, U.S. and Imperial Russia. After the division returned to Poland and was reformed into the 10th Infantry Division, Thommée served as the chief of its staff during the opening stages of the Polish-Bolshevik War until August 1919. On 22 August that year he became the head of the Third department of the staff (Offensive intelligence "B"), controlling the intelligence net in the European part of Russia, at the North-Western Front, Masovian Front and then the Polish 1st Army under Gen. Franciszek Latinik.
 Passage 3:Silvanus was born in Gaul, the son of Bonitus, a Laetic Frankish general who had supported Constantine I in the civil war against Licinius. Like so many other Franks of his times, and like his father before him, he was a loyal and thoroughly romanized "barbarian" in the military service of the Empire. By AD 351, he held the rank of tribune and was one of the senior officers who defected to Emperor Constantius II at the Battle of Mursa Major, after initially supporting the usurper Magnentius. An able soldier, Silvanus was eventually promoted to the rank of Magister militum per Gallias, a crucial post, then in AD 352-353, Constantius personally entrusted him with the difficult task of driving the Alamanni tribesmen raiding and looting in Gaul back beyond the Rhine, and restoring the fast eroding Roman authority in the province. This Silvanus fulfilled partly by bribing the Alamanni chieftains with the taxes he had collected, partly by defeating the Alamanni in battle and partly by suppressing the local bagaudae insurrections flaring up again in central and northern Gaul.

Output:
3