Problem:
Score : 200 points

Problem Statement

Takahashi has a deposit of 100 yen (the currency of Japan) in AtCoder Bank.

The bank pays an annual interest rate of 1 % compounded annually. (A fraction of less than one yen is discarded.)

Assuming that nothing other than the interest affects Takahashi's balance, in how many years does the balance reach X yen or above for the first time?

Constraints

101 \le X \le 10^{18}

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X

Output

Print the number of years it takes for Takahashi's balance to reach X yen or above for the first time.

Sample Input 1

103

Sample Output 1

3

The balance after one year is 101 yen.

The balance after two years is 102 yen.

The balance after three years is 103 yen.

Thus, it takes three years for the balance to reach 103 yen or above.

Sample Input 2

1000000000000000000

Sample Output 2

3760

Sample Input 3

1333333333

Sample Output 3

1706

Solution in OCaml (4.10.0) (judge verdict: Accepted)

open Batteries
module EnumL = Enum.Labels
module ListL = List.Labels
module ArrayL = Array.Labels

let dbg0 x = Printf.eprintf "[debug]%s\n" @@ dump x
let dbg1 x = dbg0 x; x

let id = identity

let (++) n m = List.range n `To m
let (++^) n m = if n < m then List.range n `To (pred m) else []

let scan fmt = Scanf.sscanf (read_line ()) fmt

let scan_lines n fmt f =
  if n = 0 then []
  else List.map (fun _ -> scan fmt f) (1 ++ n)

let scan_list sep cnv =
  let line = read_line () in
  (match sep with
   | None -> List.map String.of_char @@ String.to_list line
   | Some sep -> String.split_on_char sep line)
  |> List.map cnv

let scan_array ?sep cnv = Array.of_list @@ scan_list sep cnv

let scan_matrix n m e ?sep conv =
  let arr = Array.make_matrix n m e in
  ListL.iter (0 ++^ n)
    ~f:(fun i -> arr.(i) <- Array.of_list @@ scan_list sep conv);
  arr

let rec powerset e =
  match Enum.get e with
  | None -> Enum.singleton @@ Enum.empty ()
  | Some v ->
    let f = powerset e in
    let g = Enum.clone f in
    EnumL.map f ~f:(fun x -> let y = Enum.clone x in push y v; y)
    |>  Enum.append g

let permutations l =
  let rec aux l =
    let rec interleave x = function
      | [] -> [[x]]
      | (hd::tl) as lst ->
        (x::lst) ::
        (ListL.map ~f:(List.cons hd)  @@ interleave x tl)
    in
    match l with
    | [] -> [[]]
    | hd::tl -> List.concat @@ List.map (interleave hd) @@ aux tl in
  let l = List.sort (List.compare Int.compare) @@ aux @@ List.of_enum l in
  List.enum % ListL.map ~f:List.enum @@ l

let intersection l =
  EnumL.filter ~f:(fun x -> EnumL.exists ~f:((=) x) @@ Enum.clone l)

let lower_bound n f =
  let rec aux l u =
    if u - l > 1 then
      let m = (l + u) / 2 in
      if f m then aux l m
      else aux m u
    else u in aux (-1) n

let between n x m = n <= x && x < m

let x = scan "%d" id

exception Found of int

let () =
  try
    ListL.fold_left ~init:100
      ~f:(fun acc i  ->
          let w = Int.of_float @@ 1.01 *. Float.of_int acc in
          if w >= x then raise @@ Found i
          else w) (1++4000) |> ignore
  with
  | Found i -> Printf.printf "%d\n" i