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: ['l', '6819', '1029', '2925', '2361', '5545', '2151', '2681', 'f', 'p', '1263', '2875', 'b', '4665', 'f', 'g', 'p', '4829', '8453', 'z', 'l', '4219', '7517', '25', 'a', '5099', '3693', 'i', '1815', '1541', 'g', '7665']

Answer: a, b, f, g, i, l, p, z


Question: ['7997', 'm']

Answer: m


Question: ['4107', 'g', 'l', '2875', 'r', 'c', 'b', 'a', '239', '3945', 'm', '5733', '8571', '8619', 'n', 'x', 'h', '4165', '6599', 'y', 'x', 'x', 'u', 'i', 'y']

Answer:
a, b, c, g, h, i, l, m, n, r, u, x, y