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: ['6575', '2057', '2135', '6259', '7741', '4919', '7461', 'v', '401', 'h', 'u', '2391', '2181', 'y', '9273', 'd', 'b', 's', '7993', '9323', 'b', '7015']

Answer: b, d, h, s, u, v, y


Question: ['n', 'y', '7087', '9539', 'x', 'i', 'w', '7237', '8613', 'k', '5999', '4179', 'o', 'm', '7485', '1955', 'w', '1451', 'h']

Answer: h, i, k, m, n, o, w, x, y


Question: ['f', 'b', 'b', '9073', 'i', '4563', '3697', 'b', 'x', 'i', 'u', '6989', 'y', 'x', 'l', '9647', '7609', '7631', 'y', '3205', '5479', '1711', '3981', '977', '115', '2221', '1345', '3409', '4421']

Answer:
b, f, i, l, u, x, y