module Main (main) where

import qualified Data.ByteString.Char8     as C8
import           Data.Maybe

main :: IO ()
main = do
  [x,a,b] <- readInts
  putStrLn $ solve x a b

solve :: Int -> Int -> Int -> String
solve x a b = pretty (xa < xb)
  where
    xa = abs (x-a)
    xb = abs (x-b)

pretty :: Bool -> String
pretty b = if b then "A" else "B"

-- utils
readInts :: IO [Int]
readInts = map (fst . fromJust . C8.readInt) . C8.words <$> C8.getLine