object MainKt {
  @JvmStatic fun main(args:Array<String>) {
    val (x,a,b)=readLine()!!.split(" ").map(String::toInt)
    println(arrayOf(Pair(Math.abs(a-x),"A"),Pair(Math.abs(b-x),"B")).minBy{it.first}!!.second)   
  }
}
