integrate $\int_{0}^{1}\int_{3y}^{3} e^{x^2}dxdy$ 
$$\int_{0}^{1}\int_{3y}^{3}e^{x^2}dxdy$$

I understand I need to change the integration limits but just changing the order does not help to solve the integral.
$\int_{3y}^{3}\int_{0}^{1}e^{x^2}dydx=\int_{3y}^{3}[ye^{x^2}]_{0}^{1}dx=\int_{3y}^{3}e^{x^2}dx$
How should I approach it? 

$$\int_0^1\int_{3y}^3e^{x^2}\,dx\,dy=\int_{0}^{3}e^{x^2}\int_{0}^{x/3}\,dy\,dx$$
