import qualified Data.Set as S

main = do
    contents <- getContents
    let freqs = cycle $ map toInt (lines contents)
    print $ findDouble (S.empty :: S.Set Int) 0 freqs

toInt :: String -> Int
toInt (x:xs) = if x == '+'
               then read xs :: Int
               else -(read xs :: Int)

findDouble :: S.Set Int -> Int -> [Int] -> Int
findDouble history total (x:xs)
    | S.member total history = total
    | otherwise = findDouble nextHist nextTotal xs
        where nextHist = S.insert total history
              nextTotal = total + x