Consider the parallel combination of two LTI systems shown in the figure.
The impulse responses of the systems are $$ \begin{array} {} h_1(t)=2\delta (t+2)-3\delta (t+1) \\ h_2(t)=\delta (t-2). \end{array}$$ If the input $x(t)$ is a unit step signal, then the energy of $y(t)$ is ____________