import Control.Monad

rInt :: String -> Int
rInt = read

solve (a1:a2:[]) (b1:b2:[]) (c:d:[]) = a1 - (c - a2) + (if (b1 + c - a2) > d then d else b1 + c - a2)

main = do
    [as, bs, cd] <- map (map rInt . words) <$> replicateM 3 getLine
    print $ solve as bs cd