let () =
    let n = Scanf.scanf "%d\n" (fun a -> a) in 
    let lst = Array.to_list (Array.init n (fun _ -> Scanf.scanf "%d " (fun x -> x))) in 
    let v = Scanf.scanf "%d\n" (fun a -> a) in
    let s = List.fold_left (+) 0 lst in
    Printf.printf "%d\n" (s - v)