import Control.Applicative
main = getLine >>= print . solve . read

solve :: Int -> Double
solve k = fromIntegral count / 36.0
    where
        count = foldl (\acc x -> if x == k then acc + 1 else acc) 0 muls
        muls = (*) <$> [2, 3, 5, 7, 11, 13] <*> [4, 6, 8, 9, 10, 12]