object Main extends App {
  val sc = new java.util.Scanner(System.in)
  val N = sc.nextInt()
  val x :: xs = List.fill(N)(sc.nextInt() - 1)
  val B = Array.fill(N)(sc.nextInt())
  val C = Array.fill(N - 1)(sc.nextInt())
  val (_, sum) = xs.foldLeft((x, B(x))) {
    case ((l, acc), r) =>
      r -> (acc + B(r) + (if (l + 1 == r) C(l) else 0))
  }
  println(sum)
}
