import Control.Applicative ((<$>))
import Control.Monad
import Data.List

import Text.Printf

main :: IO ()
main = do
  solve <$> getl read >>= printf "%f\n"

solve :: Int -> Double
solve k = let c = fromIntegral $ length $ [xy | x <- [2,3,5,7,11,13],
                                           y <- [4,6,8,9,10,12],
                                           let xy = x * y, xy == k]
          in c / 36.0

getl :: (String -> a) -> IO a
getl f = f <$> getLine