What number season was the Brazillian central defender signed, who was previously a left back?
2012–13 FC Bayern Munich season: The 2012–13 FC Bayern Munich season was the 114th season in the club's history and the 48th consecutive season in the top flight of German football, the Bundesliga, since the promotion of the team from the Regionalliga Süd in 1965. 2012–13 FC Bayern Munich season:  Before the start of the season, Bayern signed Xherdan Shaqiri, Dante, Claudio Pizarro, Mitchell Weiser, Tom Starke and Mario Mandžukić.
i don't know