import scala.io.StdIn._

object Helpers {
  def readIntLine = readLine.split(" ").map(_.toInt)
  def readInts(n: Int) = Array.fill(n)(readInt)

  def splitDigits(i: Int): Seq[Int] = i.toString.map(_.asDigit)

  def log[A](x: A): A = {println(x); x}

  implicit class IntImplicits(val i: Int) {
    def isEven = i % 2 == 0
    def isOdd = !isEven
  }
}

object Main extends App {
  import Helpers._

  val s = readLine

  println(if (s(1) == 'B') "ARC" else "ABC")
}

