A regular "inline" calcularo accespts the operator between two operands: 2 + 3. If we have more operators and operands such a 2 + 3 * 7, we (and the computer) need to know the precedence of the operators.

In a Polish calculator we would write the operator before the operands: + 2 3. In a Reverse Polish Calculator we would write the operator after the operands: 2 3 + or 2 3 7 * +. Once we wrote down an expression the order of computation is clear. (First apply * to 3 and 7 and the apply + to the result and 2)

In this exercise you are requeted to implement a Reverse Polish Calculator that can handle +, -, *, /, and that will remove and display the last value when an = character is entered.