import Control.Applicative
import Control.Monad
import Data.List
import Data.Array
import Data.Char

main = do
  [x, a, b] <- map (read::String -> Int) . words <$> getLine
  let distA = abs (x - a)
      distB = abs (x - b)
  putStrLn $ if distA < distB then "A" else "B"
