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: ['w', '5341', 'b', '6243', 'v', '877', '1087', '6763', '5241', '3369', '9119', 't', 'v', 'j', '8261', 'o', 'b']

Answer: b, j, o, t, v, w


Question: ['7997', 'm']

Answer: m


Question: ['6867', 'o', 'i', '5657', 'm', '9781', '171', 'l', 'z', 'b', 'w', '875', 'p', '4455', 'i', 'w', '5163', 'e', 'f', 'n', 'g', '5785', 'a']

Answer:
a, b, e, f, g, i, l, m, n, o, p, w, z