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The deque ADT is defined to support the following methods: addFirst(e): Insert a new element e at the front of the deque. addLast(e): Insert a new element e at the back of the deque. removeFirst(): Remove and return the first element of the deque (null if empty). removeLast(): Remove and return the last element of the deque (null if empty). first(): Returns the first element of the deque, without removing it (null if empty). last(): Returns the last element of the deque, without removing it (null if empty). size(): Returns the number of elements in the deque. is Empty(): Returns a boolean indicating whether the deque is empty Describe how to implement the deque ADT using two stacks as the only instance variables. What are the running times of the methods