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', '4731', 'l', 'p', '1997', '601', 'n', 'l', 'p', '211', '7355', '6537', 'w', 'x', '1741', '8145', '3689', 'm', 'y', '6945']

Answer: l, m, n, p, u, w, x, y


Question: ['f', '217', '449', 't', 'j', '4097', '5561', '8317', '647', 'u', 'b', '7833', 'r', '9011', 'z', '2753', '2183', 'z', 'o', 'g', '7541', 'b', '8795', '327', 'v', 'e', 't', 'l', '4909', 'k', '7681', 'r']

Answer: b, e, f, g, j, k, l, o, r, t, u, v, z


Question: ['269', '323', '4049', 'q', '4615', 'c', '6497', 'l', '7709', 'c', 'u', 'h', 'b', '5843', 'g', '2371', 'g', 'd', 'd', 'q', 'b', '7567', 'z', '5599', 'v', 'p', '2855', '1399', '3411', '3269', 'u', 't', '5221', 's', '4609', '9899']

Answer:
b, c, d, g, h, l, p, q, s, t, u, v, z