import java.io.{BufferedReader, InputStreamReader}

object Main extends App {
  val in = new BufferedReader(new InputStreamReader(System.in))
  val Array(x, a, b) = in.readLine.split(" ").map(_.toInt)
  val xa = (a - x).abs
  val xb = (b - x).abs
  val ans = if(xa < xb) "A" else "B"
  println(ans)
}