let sosu_dice = [13; 11; 7; 5; 3; 2;]
let comp_dice = [12; 10; 9; 8; 6; 4;]

let rec can_divide n lst =
  match lst with
  | [] -> None
  | x::xs ->
    if n mod x = 0 then Some (n / x)
    else can_divide n xs

let () =
  let k = read_int () in
  let ans = match can_divide k sosu_dice with
  | None -> 0.
  | Some x ->
    match can_divide x comp_dice with
    | None -> 0.
    | Some 1 -> 1. /. 36.
    | _ -> 0.
  in
  Printf.printf "%0.13f\n" ans