let () = Scanf.scanf "%d" @@ fun x -> Printf.printf "%d\n" @@
  let cache = Array.make 4001 0 in
  cache.(0) <- 100;
  for i=1 to 4000 do
    cache.(i) <- cache.(i-1) + cache.(i-1) / 100
  done;
  List.find (fun i -> x <= cache.(i)) @@
  List.init 4001 Fun.id