Given the task definition and input, reply with output. 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.

Question: How many areas of study did Boston University offer degrees in the year Mairson began working there as a Visiting Professor? Passage 1:Flags is a 1985 album by the duo Moraz-Bruford. Unlike their prior effort Music for Piano and Drums, which featured only an acoustic drum kit and grand piano, this recording expanded their musical palette by including a Kurzweil 250 synthesizer and electronic percussion. Keyboardist Patrick Moraz and drummer Bill Bruford had both previously been members of the progressive rock band Yes (though at different points in time) and also appeared together on Chris Squire's first solo album Fish Out of Water. During the recording of this album, Moraz was a member of The Moody Blues, while Bruford's band King Crimson had just begun a hiatus that would last for ten years. Flags features ten instrumental works, including a drum solo based on Max Roach's "The Drum Also Waltzes".
 Passage 2:Mairson received a B.A. in Mathematics from Yale University in 1978 and a Ph.D. in Computer Science from Stanford University in 1984 under the supervision of Jeffrey Ullman. His Ph.D. thesis, The Program Complexity of Searching a Table, won the Machtey Award at the 1983 IEEE Symposium on Foundations of Computer Science (FOCS). Mairson was a Postdoctoral researcher at INRIA Rocqencourt from 1984 to 1985, at Stanford University in 1985, and at the University of Oxford in 1986. He held a Visiting Professor position from 1999 to 2001 at Boston University. From 2005 to 2007, Mairson has served as the Chair of the Faculty Senate at Brandeis. He is currently an Associate Editor of the journal Logical Methods in Computer Science and Information and Computation, and sits on the editorial board of Higher-Order and Symbolic Computation.
 Passage 3:Pyotr Filippovich Berestov (; , Berestovo – November 26, 1961, Zaporozhye) was a Red Army major general during the Second World War. Drafted into the Imperial Russian Army in 1917, Berestov participated in the Russian Revolution. He was drafted into the Red Army, fighting in the Russian Civil War and the Polish–Soviet War. He became a Red Army officer and served in several positions during the interwar period. Berestov was arrested and released during the Great Purge. He fought in the Winter War as a regimental commander. In the early days after the German invasion of the Soviet Union, he was given command of a People's Militia regiment, which was converted into a regular regiment. Berestov led the regiment in the early period of the Battle of Moscow and transferred to lead a regiment of the 82nd Motor Rifle Division. Berestov became the division's commander and in the spring of 1942 briefly led the 50th Rifle Division. In April, he took command of the 331st Rifle Division, which he led during the rest of the war. For his leadership, Berestov was awarded the title Hero of the Soviet Union in late June 1945. Postwar he commanded the 72nd Guards Rifle Division, which was downsized into a brigade, and the 43rd Guards Rifle Brigade, which became the 113th Guards Rifle Division. Berestov retired in 1955 and lived in Zaporizhia until his death in 1961.
2