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: ['n', '7489', 'n', 'n', '9787', '7829', 'n', '3481', 'v', 'l', '8927', 'c', 'm', 'd']

Answer: c, d, l, m, n, v


Question: ['7591', '7521', 'm', '1429', 'x']

Answer: m, x


Question: ['7143', 'g', 'p', '8689', 'u', 'g', '4759', 's', 'y', 'l', '9631', '3693', 'i', '7853', 'a', '2751', 'u', 'c', 'd', 'p', 'p', 'a', 'x', '453', 'p', '2205', '5223', '5113', 'x', 'c', '1943', 'q']

Answer:
a, c, d, g, i, l, p, q, s, u, x, y