import Control.Applicative

main :: IO ()
main = do
  { [x] <- readLineInputs :: IO [Int]
  ; print $ case divMod x 11 of
              (q, r) | r == 0 -> q * 2
                     | r <= 6 -> q * 2 + 1
                     | otherwise -> q * 2 + 2
  }


readLineInputs :: Read a => IO [a]
readLineInputs = map read . words <$> getLine
