import Control.Applicative
import Control.Monad
import qualified Data.ByteString.Char8 as B
import Data.Maybe (fromJust)
import Text.Printf
import Debug.Trace

-- or readInteger
readInts :: B.ByteString -> [Integer]
readInts = map (fst . fromJust . B.readInteger) . B.words

getInts :: IO [Integer]
getInts = liftM readInts B.getLine

main = do
  [n] <- getInts
  print $ 2 * (n `div` 3 + n `div` 5)