open System
open System.Collections.Generic;

let N =stdin.ReadLine()|>int
let A=stdin.ReadLine().Split()|>Array.map int
let B=stdin.ReadLine().Split()|>Array.map int
let C=stdin.ReadLine().Split()|>Array.map int
[<EntryPoint>]
let sf argv =
    let mutable ans = 0
    for i in [0..N-1] do
        ans <- if i>0 && A.[i]=A.[i-1]+1 then ans+C.[A.[i-1]-1]+B.[i] else ans+B.[i]
    printfn "%d" ans
    0 
