The interpreter itself is written in C++. The complete program consists of 10 classes. We will present 7 of them. Your instructor may ask you to complete this program, perhaps enhance it, and add some error checking as one of the programming projects. You are required to add the last 3 classes to complete the program. Each class is expected to be in its own file the first 7 classes are separate as the last 3 classes should be. We have the expression class (expression.h), the subexpression (subexpression.h) which classes are contained in the subexpression.cpp it has 4 classes plus.h (you must come up with the MINUS, TIMES, & DIVIDE to be added to the supexpression), operand.h only member function is contained in the operand.cpp (the operand class has two subclasses variable.h and the body of its member function evaluate is contained in the variable.cpp. The other class of the operand is literal.h. There is a symbol table that is implemented with an unsorted list (symboltable.h) member of its function are in symboltable.cpp. Finally one utility function parseName in the file parse.h and its body parse.cpp. The statements of that expression language consist of an arithmetic expression followed by a list of assignments. Assignments are separated from the expression and each other by commas. A semicolon terminates the expression. The arithmetic expressions are fully parenthesized infix expressions containing integer literals and variables. The valid arithmetic operators are +, , *, /. Tokens can be separated by any number of spaces. Variable names begin with an alphabetic character, followed by any number of alphanumeric characters. Variable names are case sensitive. This syntax is described by BNF and regular expressions in the case study. The program reads in the arithmetic expression and encodes the expression as a binary tree. After the expression has been read in, the variable assignments are read in and the variables and their values of the variables are placed into the symbol table. Finally the expression is evaluated recursively. Your first task is to complete the program provided by providing the three missing classes, Minus, Times and Divide. Next, you should extend the program so that it supports relational, logical and conditional expression operators as defined by the following extension to the grammar: -> '(' ')' | '(' ':' '?' ')' | '(' '!' ')' -> '+' | '-' | '*' | '/' | '>' | '<' | '=' | '&' | '|' You must include the following: In the conditional expression operator the symbols are reversed and the third operand represents the condition. The first operand is the value when true and the second the value when false The logical operators use single symbols not double, for example the and operator is & not && The negation operator ! is a postfix operator, not a prefix one There are only three relational operators not the usual six and the operator for equality is = not == Like C and C++, any arithmetic expression can be interpreted as a logical value, taking 0 as false and anything else as true MODIFICATIONS NEEDED: Please show me the code and where to put it to modify the below: The program should accept input from a file, allowing for multiple expressions arranged one per line. All results should be changed from double to int. In particular the evaluate function should return an int.