Scanf.scanf "%d" (fun n ->
    let a = Array.init n (fun _ -> Scanf.scanf " %d" (fun a -> a)) in
    let rec loop a =
        let q = Array.length a in
        if q = 1 then a.(0) else
            loop @@ Array.init (q - 1) (fun i -> (a.(i) + a.(i + 1)) mod 1000000007)
    in
    loop a |> Printf.printf "%d\n"
)