import           Control.Monad
import qualified Data.ByteString.Char8 as BS
import           Data.List
import           Data.Maybe

typify2 (x:y:_) = (x, y)
typify2 _       = undefined

--Input functions with ByteString
readInt = fst . fromJust . BS.readInteger

readIntTuple = typify2 . map readInt . BS.words

readIntList = map readInt . BS.words

getInt = readInt <$> BS.getLine

getIntList = readIntList <$> BS.getLine

getIntNList n = map readIntList <$> replicateM (fromIntegral n) BS.getLine

getIntMatrix = map readIntList . BS.lines <$> BS.getContents

getIntTuple = readIntTuple <$> BS.getLine

getIntNTuples n = map readIntTuple <$> replicateM (fromIntegral n) BS.getLine

getIntTuples = map readIntTuple . BS.lines <$> BS.getContents

main = do
    nums <- getIntList
    print $ solve (head nums) (nums !! 1) (nums !! 2)

solve a b c
    | n > 0 = n
    | otherwise = 0
  where
    n = c - (a - b)
