import Data.List
import Data.Char
import Data.Maybe
import qualified Data.ByteString.Char8 as BS8
 
main :: IO ()
main = do
    [a, b, c] <- unfoldr (BS8.readInt . BS8.dropWhile isSpace) <$> BS8.getLine

    print $ if (a - b) >= c
        then 0
        else c - (a - b)
