You will be given a definition of a task first, then some input of the task.
In this task, you are given a set of context paragraph and some supporting facts to answer a question. Your task is to generate answer for given question based on set of context paragraphs and supporting facts.

Context_1 : Smidjegrav Arena, formerly known as FM Mattsson Arena, is an indoor sporting arena located in Mora, Sweden. The capacity of the arena is 4,500 and it was built in 1967. It is the home arena of the Mora IK ice hockey team. It was one of two sites for the 2007 World Junior Ice Hockey Championships, along with Ejendals Arena in Leksand Context_2 : Gavlerinken Arena, formerly known as Lakerol Arena (20062014) and Gavlerinken (19672006), is an indoor sporting arena located in Gavle, Sweden. The capacity of the arena is 8,585 for ice hockey games and 11,000 for concerts which makes it the 5th largest ice hockey arena in Sweden. The arena is the home arena of the Brynas IF ice hockey team. Context_3 : Tiroler Wasserkraft Arena is an indoor sporting arena located in Innsbruck, Austria. The arena has a capacity of 3,000 people and was built in 2005 for the 2005 World Ice Hockey Championships. It is currently the home arena of HC Innsbruck who play in the Austrian Hockey League. Context_4 : Valascia is an indoor sporting arena located in Ambri, Switzerland. The capacity of the arena is 6,500 and was built in 1959. It is the home arena of the HC Ambri-Piotta ice hockey team of the National League (NL). The ends of arena are open air, making a hockey being played there partially outdoor. Context_5 : Stadio del Ghiaccio Gianmario Scola is an indoor sporting arena in Canazei, Italy. The capacity of the arena is 3,500 spectators. It is the home arena of the Sportiva Hockey Club Fassa ice hockey team of the Serie A ice hockey league. The arena also hosted games during the 1994 World Ice Hockey Championships along with the Forum di Assago in Milan and the PalaOnda in Bolzano. Context_6 : The National League (NL) is a professional ice hockey league in Switzerland. It is the top tier of the Swiss hockey league system and of the two-tier National League. Prior to the 201718 season, the league was officially called National League A. Context_7 : Platinum Arena is an indoor sporting arena located in Khabarovsk, Russia. The capacity of the arena is 7,100 and was built in 2003. It is the home arena of the Amur Khabarovsk ice hockey team of the Kontinental Hockey League, and former home of the Golden Amur hockey team of Asia League Ice Hockey. Context_8 : Arena Ugra is an indoor sporting arena located in Khanty-Mansiysk, Russia. It is used for various indoor events and is the home arena of the ice hockey team Yugra Khanty-Mansiysk which plays in the Kontinental Hockey League (previously it played in Russian Major League and lower leagues). The capacity of the arena is 5,500 spectators. Context_9 : Ice Hockey Center 2004 is an indoor sporting arena located in Chekhov, Russia. The capacity of the arena is 3,300 (originally 1,370 until 2008), making it the smallest arena in the Kontinental Hockey League. It is the home arena of the Vityaz Chekhov ice hockey team of the Kontinental Hockey League. Context_10 : The Eisstadion am Gutenbergweg (English: Gutenberg-road ice hockey venue ) is an indoor sporting arena located in Landshut, Germany. It is primarily used for ice hockey. The complex of buildings consists of two ice rinks, one generally used for training purposes. The second arena is the home venue of the Landshut Cannibals, a professional ice hockey team participating in Germany's 2nd Bundesliga. The major arena currently holds about 7,000 people. fact_1 : It is the home arena of the HC Ambri-Piotta ice hockey team of the National League (NL). fact_2 : The National League (NL) is a professional ice hockey league in Switzerland. Question: Valascia is an indoor sporting arena located in Ambri, Switzerland, it is the home arena of the HC Ambri-Piotta ice hockey team, of which professional ice hockey league in Switzerland, it is the top tier of the Swiss hockey league system?
Output:
National League