Q83b

Consider the context-free grammar $E\rightarrow E+E$ $E\rightarrow (E *E)$ $E\rightarrow \text{id}$ where $E$ is the starting symbol, the set of terminals is $\{id, (,+,),*\}$, and the set of non-terminals is $\{E\}$. For the terminal string $id + id + id + id$, how many parse trees are possible?