class PlusTree extends ExpressionTree
{   ExpressionTree first; ExpressionTree second;

    public PlusTree(ExpressionTree f, ExpressionTree s) {first=f;second=s;}
    
    public void printStackCode()
       {first.printStackCode();
        second.printStackCode();
        System.out.println("PLUS");}
    
    public void printExpression()
       {System.out.print("(");
        first.printExpression();
        System.out.print("+");
        second.printExpression();
        System.out.print(")");}
    
    public void printLispCode()
       {System.out.print("(PLUS");
        first.printLispCode();
        second.printLispCode();
        System.out.print(")");}
}