Let $$f : R \rightarrow R$$ be a function defined by $$f(x) = \begin{cases}[x], & x \leq 2\\0 & x > 2\end{cases}$$,
where [x] is the greatest integer less than or equal to x. If $$I = \int_{-1}^{2} \frac {xf(x^2)}{2 + f(x + 1)} dx,$$ then the value of (4I - 1) is