Q52

Consider the queues $Q_{1}$ containing four elements and $Q_{2}$ containing none (shown as the $\textsf{Initial State}$ in the figure). The only operations allowed on these two queues are $\textsf{Enqueue (Q, element)}$ and $\textsf{Dequeue (Q)}.$ The minimum number of $\textsf{Enqueue}$ operations on $Q_{1}$ required to place the elements of $Q_{1}$ in $Q_{2}$ in reverse order (shown as the $\textsf{Final State}$ in the figure) without using any additional storage is________________.