Design a four-bit counterlike circuit controlled by the input w. If w=1, then the counter adds 2 to its contents, wrapping around if the count reaches 8 or 9. Thus if the present state is 8 or 9, then the next state becomes 0 or 1, respectively. If w=0, then the counter subtracts 1 from its contents, acting as a normal down-counter. Use D flip-flops in the circuit.