import Control.Monad.ST
import Control.Monad
import Data.Array.ST
import Data.Array
import Data.STRef
import Control.Monad
import Control.Applicative
import Data.List
main = do
  getLine
  a <- map read <$> words <$> getLine ::IO [Integer]
  b <- readLn::IO Integer
  print $ (sum a) - b