-- ABC 136 A
import Data.Maybe
import Data.Char
import Data.Bool
import Data.List
import qualified Data.ByteString.Char8 as BS
import qualified Data.Vector.Unboxed as VU

main :: IO()
main = do
  [a, b, c] <- getIntList
  print $ solve a b c

solve :: Int -> Int -> Int -> Int
solve a b c = bool id (const 0) =<< (<0) $ c - (a - b)

-- ByteStringを用いた入力
readInt = fst . fromJust . BS.readInt

-- 空白区切りの整数列をListで受け取る
getIntList = unfoldr (BS.readInt . BS.dropWhile isSpace) <$> BS.getLine