Background: Atsuko Maeda (Qian Tian  Dun Zi , Maeda Atsuko, born July 10, 1991, in Ichikawa, Chiba) is a Japanese singer and actress known for her work in the Japanese idol group AKB48. Maeda was one of the most prominent members in the group, and placed first among all AKB48 and sister group candidates in the group's general 2009 and 2011 elections, and second in the 2010 election. She also appeared on many of its album covers. On March 25, 2012, she announced her graduation from AKB48; it was held on August 27.
Context: At age 14, Maeda became a member of AKB48's first group, Team A, which composed of 24 girls and debuted on December 8, 2005.  In 2009, Maeda won the first edition of AKB48's annual general elections, which are described as a popularity contest. As a result, she was the headlined performer for the group's 13th single, "Iiwake Maybe". The following year, she placed second overall, but still had a significant choreography position in the lineup for "Heavy Rotation". Later that year, AKB48 employed a rock-paper-scissors tournament to determine the top spot of AKB48's 19th major single "Chance no Junban". Maeda placed 15th, which secured her a spot on title track. Maeda would also win the group's third general election held in 2011.  Maeda was one of the members who sang on every AKB48 title track since the group's inception. Her streak of A-side appearances ended in 2011, when she lost to Team K captain Sayaka Akimoto at a rock-paper-scissors tournament which determined the featured members for the group's 24th single "Ue kara Mariko".  On March 25, 2012, during an AKB48 Concert at the Saitama Super Arena, Maeda announced that she would leave the group. This caused a large buzz in the Japanese news, and spawned a rumor (later proved false) that a student from University of Tokyo had committed suicide over the announcement. AKB48 later announced that Maeda would leave after the Tokyo Dome concerts; For her final performance, there were 229,096 requests filed for seat tickets. Her farewell performance and ceremony occurred on August 27 at the AKB48 theater, and was streamed live on YouTube.
Question: How many teams are in AKB48?. Whats the answer?