solve :: Int -> Int -> Int -> String
solve x a b
    | da < db = "A"
    | otherwise = "B"
    where
        da = abs (x - a)
        db = abs (x - b)


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