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', '6291', '3939', '9569', 'u', '1635', '3359', '8335', 'n', '2799', '7359', 'k', 'm', '2817']

Answer: k, m, n, u, w


Question: ['r', 't', '3539', 'z', 't', '6055', 'r', '5787', '8469', 'p', 'h', '9729', 'z', '1637', '5873', 'c', '3597', '4411', 's', 'k', 'q', '6471', '5375', 'e', 'v', 'i', '7425', 'h', '9079', 'd', '1585', '6011', 'x', '5669', '5219', '4951', '4765', '8285', '2811', 'c', '1805', '6463']

Answer: c, d, e, h, i, k, p, q, r, s, t, v, x, z


Question: ['7321', 'u', 't', 'c', 'k', '9877', 'b', '363', '8223', '3133', '8257', 'l', '7565', 's', '61', '1', '9869', '6873', '3387', 'g', 'z', '7373', 'b', '4547', '8129', 'r', 'e', '7249', '529', 'x', '1477', '9149', 'v']

Answer:
b, c, e, g, k, l, r, s, t, u, v, x, z