In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
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Question: ['u', '4731', 'l', 'p', '1997', '601', 'n', 'l', 'p', '211', '7355', '6537', 'w', 'x', '1741', '8145', '3689', 'm', 'y', '6945']

Answer: l, m, n, p, u, w, x, y


Question: ['u', 'd', '4193', '5687', 'p', 'r', '7787', 't']

Answer: d, p, r, t, u


Question: ['541', '4365', '401', 'g', 'v', '5843', '4365', '3481', 'e', '4837', '4613', 'f', '5727', 'v', 'w', 'l', 's', '7753', 'y', '7485', '3587', 'v', 'z', 'l', '7155', 'e', 'c', 'v', 'h', '2537', '5769', '6009', 'g', '7133', '2199', 'v', '4733', 'o', 't']

Answer:
c, e, f, g, h, l, o, s, t, v, w, y, z