#! /usr/bin/env stack
-- stack --resolver lts-12.20 --install-ghc script
module Main where

import Data.List (scanl')
import qualified Data.Set as S

loopRight :: b -> (b -> Either a b) -> a
loopRight b f = case f b of
   Left  a  -> a
   Right b' -> loopRight b' f

main :: IO ()
main = interact $ show . \input ->
   let changes  = fmap (read . dropWhile (=='+')) $ lines input
       freq     = scanl' (+) 0 (cycle changes)
   in loopRight (S.empty, freq) $ \(s, f:fs) ->
         if S.member f s then Left (f :: Int) else Right (S.insert f s, fs)