import Control.Applicative ((<$>))
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B

import Data.List (unfoldr)
import Data.Char (isSpace)

main :: IO ()
main = getLine >> solve <$> readil B.readInt <$> B.getLine >>= putStrLn

solve :: [Int] -> String
solve xs | even s = "B"
         | otherwise = if filter (>= 2) xs == [2] then "A" else "B"
  where s = sum xs

readil :: Integral a =>  (ByteString -> Maybe (a, ByteString)) -> ByteString -> [a]
readil f = unfoldr g
  where
    g s = do
      (n, s') <- f s
      return (n, B.dropWhile isSpace s')