open List

let _ = while true do
  match fold_left
      (fun s w ->
        let f op = match s with
        | h1 :: h2 :: t -> op h2 h1 :: t
        | _ -> failwith "Stack underflow"
        in
        match w with
        | "+" -> f ( +. )
        | "-" -> f ( -. )
        | "*" -> f ( *. )
        | "/" -> f ( /. )
        | _ -> (float_of_string w) :: s)
      [] (Str.split (Str.regexp "[ \t]+") (read_line ())) with
  | h :: [] -> print_endline (string_of_float h)
  | _ -> failwith "Malformed expression"
done