Define a class called Counter. An object of this class is used to count things so it records a count that is a non-negative whole number. Include methods to set the counter to 0, to increase the counter by 1, and to decrease the counter by 1. Be sure that no method allows the value of the counter to become negative. Also include an accessor method that returns the current count value, as well as a method that displays the count on the screen. Do not define an input method. The only method that can set the counter is the one that sets it to zero. Write a program to test your class definition. (Hint: you need only one instance variable).