{-# LANGUAGE LambdaCase #-}
{-# OPTIONS_GHC -Wno-unused-imports -Wno-unused-top-binds #-}
import Control.Monad
import Data.Maybe
import qualified Data.ByteString.Char8 as BS
import Control.Monad.ST             
import Data.Ix
import Data.Array (Array)
import Data.Array.IArray
import Data.Array.IO             
import Data.Array.MArray          
import Data.Array.ST                
import Data.Array.Unboxed (UArray)
import Data.Char
import Data.List as L
import Data.Foldable
import Data.Function
import Control.Exception
import Data.Array.Base (STUArray(STUArray), UArray (UArray))
import Data.Array.IO.Internals (IOUArray(IOUArray))
import Data.Ord
import GHC.Float

main :: IO ()
main = do
  n <- getInt
  let 
    ns = [1 .. n]
    ans = length $ filter (elem '8') $ map show ns
  print ans



--library--------------
modulus :: Int
modulus = 10 ^ 9 + 7
addMod, subMod, mulMod :: Int -> Int -> Int
addMod x y = (x + y) `mod` modulus
subMod x y = (x - y) `mod` modulus
mulMod x y = (x * y) `mod` modulus
tuplify2 :: [b] -> (b, b)
tuplify2 (x:y:_) = (x,y)
tuplify2 _ = undefined

readInt :: BS.ByteString -> Int
readInt = fst . fromJust . BS.readInt
readIntTuple :: BS.ByteString -> (Int, Int)
readIntTuple = tuplify2 . map readInt . BS.words
readIntList :: BS.ByteString -> [Int]
readIntList = map readInt . BS.words

getInt :: IO Int
getInt = readInt <$> BS.getLine