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: ['6143', 'y', '5505', '9813', 'r', 'v', 'u', '8681', '2387', 'u', 'o', 'm', '9793', 'm']

Answer: m, o, r, u, v, y


Question: ['9113', '3625', 'u', '8189', '3649', '259', '5539', '1583', 'g', '4037', 'y', 'v', '8337', 'd', 'q', 'j', 'c', 'h', 'p', '1601', 'z', 'c', 'n', '1767', '1679', '1805', 'm', '4469', '2487', '6015', '973']

Answer: c, d, g, h, j, m, n, p, q, u, v, y, z


Question: ['f', 'u', '4363', 'b', '2455', 'b', '5657', '5715', 'r', '7073', 's', 'd', 'i', 't', 'j', '3783', 'f', 'e', '1873', 't', '5161', 'l', '1717', 'o', 'x', 'c', '7467', '8993', 'w', 'p', 'w', '8257', 'h', 't', '9861', '8591', '8695', 's', 'b', 'c', 'k']

Answer:
b, c, d, e, f, h, i, j, k, l, o, p, r, s, t, u, w, x