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: ['k', 'r', 'f', '4369', 'z', 'z', 'l', '143', 'r', '707', '9167', 'g', '1749', 'i']

Answer: f, g, i, k, l, r, z


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

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


Question: ['v', '5217', 'f', 'y', 'i', 'r', 'y', 'q', '3553', 'k', 't', '9263', 'e', '5331', '715', 'm', '7843', '3623', 'y', '3355', '6307', '9967', '7291']

Answer:
e, f, i, k, m, q, r, t, v, y