fun readInt () =
    valOf (TextIO.scanStream (Int.scan StringCvt.DEC) TextIO.stdIn)

val () =
    let
        val k = readInt ()
        val allCases =
            List.foldl
                (fn (x, acc) =>
                    acc @
                    List.map
                        (fn y =>
                            x * y)
                        [4, 6, 8, 9, 10, 12]
                )
                []
                [2, 3, 5, 7, 11, 13]
                 
        val ans =
            (Real.fromInt
                 (List.length
                      (List.filter
                           (fn x =>
                               x = k)
                           allCases)))
                / 36.0
    in
        print (Real.toString ans ^ "\n")
    end