{-# OPTIONS_GHC -O2 -funbox-strict-fields #-}
import qualified Data.ByteString.Char8 as BS
import           Data.Maybe            (fromJust)

main :: IO ()
main = do
  [x, a, b] <- map readInt . BS.words <$> BS.getLine
  putStrLn $ solve x a b

solve :: Int -> Int -> Int -> String
solve x a b = if abs (x - a) < abs (x - b) then "A" else "B"

readInt :: BS.ByteString -> Int
readInt = fst . fromJust . BS.readInt
