import Control.Monad
import Control.Applicative
import Data.List
import qualified Data.Map as Map
import Data.Array
strToInt s = (read :: String -> Int) s

main = do
    x <- readLn
    print $ solve x

solve x = 2 * ele + moda
          where ele = div x 11
                moda = if (mod x 11) == 0
                       then 0
                       else if (mod x 11) <= 6
                            then 1
                            else 2