4. (20 pts) Given the following grammar: Kstmt> ::- if then 1 if then else I other : := true false where other is a terminal that stands for any other kinds of statements (a) (10 pts) This grammar is ambiguous. Give a string having two different parse (b) (10 pts) If we adopt the disambiguating rule (used in most languages) "match trees and draw the parse trees. each else with the closest previous unmatched then," write an equivalent, un ambiguous grammar