instruction:
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.
question:
['2313', '2073', 'd', 'e', 'o', '793', '4999', 'f', 'c', '4473', '4519', 'u', 'n', 'k', '69', '475', 'a', 'j', 'q', 'x', '5869', '9523', 'z', 'v', '9265', '5989', 'p', 'm', 'g', 'y', 'b']
answer:
a, b, c, d, e, f, g, j, k, m, n, o, p, q, u, v, x, y, z


question:
['8301', 'd', 'p', 'l', 'm', '9099', 'o', '8045', 'e', 's', 't', '8853', 'v', '6375', 'q', '2505', 's', '4219', '3587', 'g', '651', '7129']
answer:
d, e, g, l, m, o, p, q, s, t, v


question:
['9715', '2693', '509', '5705', '6317', '3013', 'z', 'y', 'd', 'k', '5061', '3947', 'u', 'c', '5831', '3549', 'g', '1065', 'a', 'a', '6761', 'x', 'k', '7751', 'n', 'y', 'e', '2835', '8115', 'f', '6077', 'u', '1221', 'e', '6701', '7509', '7609', '8253', '9677', '4295', 'j', '3113', '4101']
answer:

a, c, d, e, f, g, j, k, n, u, x, y, z