let f () = Scanf.scanf " %d" (+) 0
let n = f ()
let a_s = Array.init n @@ fun _ -> f ()
let bs = Array.init n @@ fun _ -> f ()
let cs = Array.init (n - 1) @@ fun _ -> f ()
let ans = ref @@ Array.fold_left (+) 0 bs
let _ = for i = 0 to n - 2 do if a_s.(i + 1) = a_s.(i) + 1 then ans := !ans + cs.(a_s.(i) - 1) done; Printf.printf "%d\n" !ans