18. (10 points) Based on the following grammar, draw an annotated parse tree that shows how the syntax tree for a-(b+c) is constructed. mknode() is a function that creates a node for a syntax tree. A good way to do this is to first draw the parse tree, then annotate the leaves and propogate the annotations 3 up the tree. After you're done, E.n of the root of the parse tree will be the abstract syntax tree. Your parse tree will look something like the following: You can see that this particular