The first derivative of a function \( f \in C^\infty(-3, 3) \) is approximated by an interpolating polynomial of degree 2, using the data
\[
(-1, f(-1)), (0, f(0)) \text{ and } (2, f(2)).
\]
It is found that
\[
f'(0) \approx -\frac{2}{3} f(-1) + \alpha f(0) + \beta f(2).
\]
Then, the value of \( \frac{1}{\alpha \beta} \) is