import Control.Applicative ((<$>))
import Data.Char (isDigit)
import Control.Monad.State

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

solve :: String -> Int
solve = evalState expr

num :: State String Int
num = do
  ss@(x:xs) <- get
  case x of
   '+' -> do put $ dropWhile isDigit xs
             return . read . takeWhile isDigit $ xs
   '-' -> do put $ dropWhile isDigit xs
             return . negate . read . takeWhile isDigit $ xs
   _ -> do put $ dropWhile isDigit ss
           return . read . takeWhile isDigit $ ss

op :: State String (Int -> Int -> Int)
op = do
  (x:xs) <- get
  case x of
   '+' -> do put xs
             return (-)
   _ -> do put xs
           return (+)

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