module Main (main) where
import Control.Applicative
import Control.Monad
import Data.List

main :: IO ()
main = do
 { n <- readLn :: IO Int
 ; cs <- map read . words <$> getLine :: IO [Int]
 ; let ones = length $ filter (==1) cs
 ; let bigs = length $ filter (>1) cs
 ; let answer = if bigs > 0 || even ones then "B" else "A"
 ; putStrLn answer
 }