// http://yukicoder.me/problems/1039
open System

let dprintfn fmt = Printf.kprintf Diagnostics.Debug.WriteLine fmt

[<EntryPoint>]
let main argv = 
    let N = Console.ReadLine().Trim() |> int
    let A = Console.ReadLine().Trim().Split([|' '|]) |> Array.map int64
    let v = Console.ReadLine().Trim() |> int64
    let a = Array.sum A
    printfn "%d" <| (a - v)
    0 // 整数の終了コードを返します