let () =
  Scanf.scanf "%d\n" @@ fun n ->
  let lst = ref (Array.to_list
    (Array.init n @@ fun _ -> Scanf.scanf "%d " @@ fun d -> d)) in
  for i = 0 to n - 2 do
    let (_,nowlst) = List.fold_left
      (fun (bfr, lst) x -> (x, ((bfr+x) mod 1000000007) :: lst)) (List.hd !lst, []) (List.tl !lst) in lst := nowlst;
  done;
  Printf.printf "%d\n" ((List.hd (!lst)) mod 1000000007)