Integrate $f(x,y,z) = x + \sqrt{y} - z^2$ over the path from $(0,0,0)$ to $(3,9,3)$ given by
$C_1 : \mathbf{r}(t) = t\mathbf{i} + t^2\mathbf{j}$, $0 \le t \le 3$
$C_2 : \mathbf{r}(t) = 3\mathbf{i} + 9\mathbf{j} + t\mathbf{k}$, $0 \le t \le 3$.
$\int_C (x + \sqrt{y} - z^2) \, ds = \boxed{}$