Question: Where is the club located that Silvan Hefti played for?

full_context: Document 1: FC Zürich: Fussballclub Zürich, commonly abbreviated to FC Zürich, FCZ or simply Zürich, is a Swiss football club based in the city of Zürich and currently playing in the Super League, the first tier in the Swiss football league system. The club was founded in 1896 and has won the Swiss Super League 12 times and the Swiss Cup nine times. The club won the 2009 Swiss Super League and last won the Swiss Cup in 2016. They play their home games at the Letzigrund in Zürich, which seats 25,000 spectators. For the women's team see FC Zürich Frauen.
Document 2: Silvan Hefti: Silvan Hefti (born 25 October 1997) is a Swiss footballer who plays for FC St. Gallen.
Document 3: Adonis Ajeti: Adonis Afrim Ajeti (born 26 February 1997) is a Swiss professional footballer of Albanian descent who plays as a defender for Swiss club FC St. Gallen. He is the twin brother of Albian Ajeti who plays for German club Augsburg and the younger brother of Arlind Ajeti who plays for Italian Serie A club Torino. Adonis hold dual citizenship, the Swiss where he was born and grown up and the Albanian citizenship due to his parents origin.
Document 4: Son Heung-min: Son Heung-min (Hangul: 손흥민 ; Hanja: 孫興慜 ; ] ; born 8 July 1992) is a South Korean professional footballer who plays as a winger or a forward for Premier League club Tottenham Hotspur and the South Korea national team.
Document 5: 2016–17 Ergotelis F.C. season: The 2016–17 season was Ergotelis' 87th season in existence and 1st season in the Gamma Ethniki, the third tier of the Greek football league system, after 14 years in which the club competed in professional competitions. Ergotelis also participated in the Gamma Ethniki Cup, a football competition cup in which only the clubs competing in one of the four groups of the Gamma Ethniki can participate. The season marked the beginning of a new era in the club's history, as the previous Football Club opened winding-up proceedings entering into liquidation, a process that allowed the parent sport club G.S. Ergotelis to form a new football department eligible to compete in the Gamma Ethniki under new leadership, free of the financial obligations of the previous administration. The club slogan for the season "Ksekiname!" (Greek: Ξεκινάμε! ) literally translates to "We begin!". The project was successful, as Ergotelis finished as Champions of Group 4, achieving instant promotion to the Football League, and professional divisions in general.
Document 6: Bastian Schweinsteiger: Bastian Schweinsteiger (] ; born 1 August 1984) is a German professional footballer who plays as a midfielder for Major League Soccer club Chicago Fire. A right-footed player, he usually plays as central midfielder. Earlier in his career, he primarily played as a wide midfielder.
Document 7: Tranquillo Barnetta: Tranquillo Barnetta (] ; born 22 May 1985) is a Swiss professional footballer who plays as a midfielder for St. Gallen. He usually plays out wide as a left winger but can also play in the centre as an attacking midfielder, or even in a more withdrawn role as a central midfielder. Barnetta is known for his "extreme pace, mobility and creativity". Prior to moving to the MLS, Barnetta played football for several Swiss and German clubs. At international level, he has amassed 75 caps for the Swiss national team, representing his nation in three FIFA World Cups, and two UEFA European Football Championships.
Document 8: FC Sion: FC Sion is a Swiss football team from the city of Sion (] ). The club was founded in 1909, and play their home games at the Stade Tourbillon. They have won the Swiss Super League twice, and the Swiss Cup in thirteen of their fourteen appearances in the final, the most recent being in 2015.
Document 9: FC Luzern: Fussball-Club Luzern, commonly known as FC Luzern (] ), or simply abbreviated to FCL, is a Swiss sports club based in Lucerne. It is best known for its professional football team, which plays in the Super League, the top tier of the Swiss football league system, and has won the national title once and the national cup twice.
Document 10: FC St. Gallen: FC St. Gallen 1879 ("Fussballclub St. Gallen 1879") is a Swiss football club based in St. Gallen. The club is currently playing in the 2016–17 Swiss Super League.
Document 11: FC Thun: FC Thun ("Fussballclub Thun 1898") is a Swiss football team from the Bernese Oberland town of Thun. The club currently plays in the Swiss Super League after being promoted in the 2009/10 season. The club plays at the Stockhorn Arena which accommodates a total of 10,000 supporters, both seated and standing. The club's colours are red and white.
Document 12: Dennis Hediger: Dennis Hediger (born 22 September 1986, in Switzerland) is a Swiss professional footballer who currently plays as a midfielder for FC Thun in the Swiss Super League.
Document 13: Silvan Aegerter: Silvan Aegerter (born 5 May 1980, in Grenchen) is a Swiss football midfielder who currently plays as midfielder for FC Lugano in the Swiss Challenge League. Before he played for FC Thun and FC Zürich. He played in the youth team for his local team FC Grenchen and also for FC Basel.
Document 14: FC Basel: FC Basel 1893 ("Fussball Club Basel 1893"), widely known as FC Basel or just Basel, and sometimes referred to as FC Basel in English or FCB, is a Swiss football club based in Basel. They are one of the most successful clubs in Swiss football, having won the Swiss Super League 20 times, the second most for any Swiss club.
Document 15: FC Lausanne-Sport: FC Lausanne-Sport (also referred to as LS) is a Swiss football club based in Lausanne.
ground_truth: St. Gallen