import qualified Data.IntMap as M
import Text.Printf

main = readLn >>= printf "%.12f" . complete

complete :: Int -> Double
complete n = M.findWithDefault 0 6 $ foldl dp (M.singleton 0 1) [1..n]

dp m k = M.fromListWith (+) (filter (\(k,_) -> k<=6) next)
  where
    next = concatMap (\(i,p) -> let j = fromIntegral i in [(i+1, p*((6-j)/6)), (i, p*(j/6))]) $ M.toList m