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', 'd', '4193', '5687', 'p', 'r', '7787', 't']

Answer: d, p, r, t, u


Question: ['s', 'j', '6779', '1535', 'd', 'e', 'u', '3023', '241', '9115', 'h', '8003', '3755', 'q', 'm', '2725', 'x', 'y', 'n', 'm', 'j']

Answer: d, e, h, j, m, n, q, s, u, x, y


Question: ['o', 'u', '4127', '2251', 'd', 'p', '7361', 'w', 'r', 'i', '3899', '7383', '605', 'f', '4931', 'y', 'n', '9693', 'i', '4315', 'j']

Answer:
d, f, i, j, n, o, p, r, u, w, y