import Control.Applicative ((<$>), (*>))
import Text.Parsec
import Text.Parsec.String (Parser)

main :: IO ()
main = solve <$> getLine >>= print

solve :: String -> Int
solve = either (const 0) id . parse expr ""

num :: Parser Int
num = do
  f <- (char '+' *> return id) <|> (char '-' *> return negate) <|> return id
  d <- many1 digit >>= return . read
  return $ f d

op :: Parser (Int -> Int -> Int)
op = char '+' *> return (-) <|> char '-' *> return (+)

expr :: Parser Int
expr = do
  x <- num
  f <- op
  y <- num
  return $ f x y