import scala.io.StdIn._
import scala.math._

object Main extends App{
  val sc = new java.util.Scanner(System.in)
  val x = sc.nextInt
  val a = sc.nextInt
  val b = sc.nextInt
  if(abs(x-a)<abs(x-b)){
    println("A")
  }
  else{
    println("B")
  }
}
