module Main where
    import Data.List

    main = do
        ns <- words <$> getLine 
        let x = (read (ns !! 0) ::Int)
        let a = (read (ns !! 1) ::Int)
        let b = (read (ns !! 2) ::Int)
        if (abs (a-x)) < (abs (b-x)) 
            then
                putStrLn "A"
            else
                putStrLn "B"
