import Data.Bits

main :: IO ()
main = getLine >> getLine >>= putStrLn . yesno . solve . filter (>0) . map read . words

yesno :: Bool -> String
yesno True = "A"
yesno False = "B"

solve :: [Int] -> Bool
solve a
  | all (==1) a = if odd (length a) then True else False
  | (length . filter (==2) $ a) == 1 && (length . filter (> 2) $ a) == 0 = if odd (length a) then False else True
  | otherwise   = False