Merge pull request #26 from vu3rdd/master

Exercise 1: "int" is an "exp" as well

book.tex

@@ -929,7 +929,7 @@ output that takes the form of the $\itm{residual}$ non-terminal in the
 following grammar.
 \[
 \begin{array}{lcl}
-\Exp &::=& (\key{read}) \mid (\key{-} \;(\key{read})) \mid (\key{+} \; \Exp \; \Exp)\\
+\Exp &::=& \Int \mid (\key{read}) \mid (\key{-} \;(\key{read})) \mid (\key{+} \; \Exp \; \Exp)\\
 \itm{residual} &::=& \Int \mid (\key{+}\; \Int\; \Exp) \mid \Exp
 \end{array}
 \]