let pow x n =
  let rec doit x n acc =
    if n = 0 then acc
    else doit (x * x) (n / 2) (if n mod 2 = 0 then acc else acc * x) in
  doit x n 1

let () =
  let n = read_int () in
  let rec doit i =
    if pow 2 i >= n then i
    else doit (i + 1) in
  doit 0 |> Printf.printf "%d\n"