-- Ω\・8・)ﾁｭｰﾝ

import Control.Applicative
import Text.Printf

main = do
  k <- readLn
  let p :: Double
      p = (/36) $ fromIntegral $ length $ filter (==k) $ (*) <$> [2,3,5,7,11,13] <*> [4,6,8,9,10,12]
  printf "%.13f\n" p