Q4. [20 marks] Implement a function Copy(Stack S1, Stack S2) in pseudocode to copy the elements of S2 to an empty stack S such that Si is the same as S2. In this question, only the methods of the Stack ADT are allowed. For convenience, assume that the Stack ADT also provides a method, named Size, which returns the size of the corresponding stack; that is, S.SIZE() returns the # of elements in stack S. Denoting the size of S1 and S2 by |S1|and |S2], respectively, give the time complexity of your algorithm. Assuming the S and S2 in Fig. 1 are fed to your algorithm, illustrate your algorithm by showing the contents inside each of the stacks involved after each operation. Hint: you can use an extra stack S3 to transfer elements. 6 4 3 Si S2 Fig. 1. An Instance of S and S2