open System
open System.Collections.Generic

[<AutoOpen>]
module Cin =
    let read f = stdin.ReadLine() |> f
    let reada f = stdin.ReadLine().Split() |> Array.map f
    let readChars() = read string |> Seq.toArray
    let readInts() = readChars() |> Array.map (fun x -> Convert.ToInt32(x.ToString()))

[<AutoOpen>]
module Cout =
    let writer = new IO.StreamWriter(new IO.BufferedStream(Console.OpenStandardOutput()))
    let print (s: string) = writer.Write s
    let println (s: string) = writer.WriteLine s
    let inline puts (s: ^a) = string s |> println

let solve() =
    let k = read int
    let a = [| 2; 3; 5; 7; 11; 13 |]
    let b = [| 4; 6; 8; 9; 10; 12 |]

    let pr =
        [| for i in 0 .. 5 do
            for j in 0 .. 5 do
                yield a.[i] * b.[j] |]

    let cnt = Array.filter (fun p -> p = k) pr |> Array.length
    float cnt / 36.0 |> puts
    ()

[<EntryPoint>]
let main _ =
    try
        solve()
    with e -> printfn "%s" (e.ToString())
    writer.Close()
    0 // return an integer exit code