let rec range a b = if a >= b then [] else a::(range (a+1) b)
let rec sum = function [] -> 0 | n::ns -> n + (sum ns)

let solve ls =
  let rec inner ls prev cur must =
    match ls with
    | [] -> cur @ must
    | x::xs -> 
       if cur == [] then inner xs prev [x] must
       else if x > (List.hd cur) then inner xs cur (x::prev) must
       else inner xs [] [] cur
  in inner ls [] [] []

let _ =
  let _ = int_of_string @@ read_line() in
  let inputs = String.split_on_char ' ' (read_line ()) in
  inputs 
  |> List.map (fun s -> int_of_string s)
  |> solve 
  |> sum
  |> print_int