import qualified Data.ByteString.Char8 as BS
import Data.Char
import Debug.Trace
import Data.List (unfoldr)
import Control.Monad
import qualified Data.Vector.Unboxed as UV

main = do
    [a, b, c] <- unfoldr (BS.readInt . BS.dropWhile isSpace) <$> BS.getLine
    print $ if a - b > c then 0 else c - a + b
