Instructions: 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.
Input: Question: How old was Alikhanov when Pomeranchuk studied with him? Passage 1:McCammon never played in the NHL, spending his entire career in the minor leagues. He was the head coach of the Maine Mariners of the American Hockey League and won the Calder Cup in 1977-78 and 1978–79, the first two years of the team's existence. McCammon had two stints as head coach of the Philadelphia Flyers, also serving as the team's general manager during the latter. He was also the head coach of the Vancouver Canucks and an assistant coach for the Edmonton Oilers on two different occasions. With Vancouver in 1988–89, he was runner-up to Pat Burns of the Montreal Canadiens for the Jack Adams Trophy as NHL Coach of the Year. He won the Stanley Cup with the Edmonton Oilers in 1987 as director of player development, and in 2002 and 2008 as a scout with Detroit. McCammon's name was added to the Stanley Cup in 2002 with Detroit. 
 Passage 2:After Landau moved to the Kapitza institute in Moscow (to avoid arrest for comparing Stalinism to Nazism), Pomeranchuk also moved there, working for the tanning industry. He returned to Leningrad in 1938, lecturing, completing his Ph.D. and becoming employed as a junior scientist. He joined the Lebedev Institute of the Academy of Sciences of the USSR in Moscow as a senior scientist in 1940. In 1941 the institute was evacuated to Kazan. Under Abraham Alikhanov, he studied cosmic rays in Armenia from 1942. In 1943, he transferred to Laboratory No.2 under Igor Kurchatov as part of the Soviet project to develop nuclear weapons. Alikhanov founded Laboratory No.3 (which became the Institute for Theoretical and Experimental Physics (ITEP)) and Pomeranchuk worked there from 1946 (and for the rest of his life), founding and leading the Theoretical department, as well as being Professor of Theoretical Physics at the Moscow Mechanical Institute where students admired his infectious enthusiasm for his subject. Rudolf Peierls was consoled by the fact that it was "very clever Pomeranchuk" - and no-one else - who corrected his 1/T law for heat conduction in high-temperature condensed matter physics. His work in the 1940s was dominated by neutron research and his manuscript with Akhiezer was the basic guide for Soviet nuclear reactor construction. In 1950, he published a paper suggesting that the entropy of helium-3 as a liquid was less than as a solid. In 1950, Pomeranchuk received an order from Josef Stalin to go to Arzamas-16, located in the closed city of Sarov, Nizhny Novgorod region, to work on Soviet nuclear weaponry. Missing his family and his 'hobby physics' problems, he was advised not to apply for a revocation but wait until the order was "forgotten." He returned to ITEP within a year. He continued enthusiastically with work on quantum field theory and S-matrix theory, particle collisions and Regge theory, the latter in vigorous collaboration with Vladimir Gribov. His last paper on Regge theory was published posthumously. For his work, Pomeranchuk was twice awarded the Stalin Prize (1950, 1952). He was elected a corresponding member of the Academy of Sciences of the USSR in 1953 and full member in 1964.
 Passage 3:After playing junior hockey for the Sioux Falls Stampede of the United States Hockey League (USHL), Vanek joined the University of Minnesota Golden Gophers, leading the team in goals (31), assists (31) and points (62) in the 2002–03 season. In part due to his prolific scoring touch, the Golden Gophers won the 2003 NCAA National Championship. Vanek was named MVP of the Frozen Four tournament, scoring the game-winning goals in both the semifinal against Michigan in overtime and in the final against New Hampshire. He was also named Minnesota's team MVP for 2003, becoming the first freshman to receive the honor. He scored the most points by a Golden Gopher freshman in 2003 since Aaron Broten who scored 72 total points in 1979–80. He was the first freshman to lead the team in scoring since Mike Antonovich in 1969–70. His 31 goals also led all NCAA freshmen in goal scoring, and was fourth in the entire country. He was also the 2003 WCHA Rookie of the Year, the third Golden Gopher to win the award.

Output:
2