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:
['r', 'n', '7583', '8697', '7927', 'l', '5003', '1363', 'p', 'e', 'q', '6227', '6915', '8619', '9011', 'n', '3063', '3799']
answer:
e, l, n, p, q, r


question:
['3651', 'c', 'm', '7123', '2981', '9649', 'o', '2181', 'h', '8577', 'a', '5027', 'x', 'u', '1039', '347', '8219', 'c', '1063', '8885', 'f', 'd', '3067', '2509', 'i', 's', '5509', '2003', 'h', '8869', 'x', 'd', '5141', 'h', 'i', 'b', 'o']
answer:
a, b, c, d, f, h, i, m, o, s, u, x


question:
['p', 'o', 'l', 'g', 'f', '6493', 'v', 'i', 'j', '2561', 'p', '609', '2985', '7617', 'a', 'c', '6033', '5571', 'm', 'q', '9855', 'f', 'u', 'y', '1075', '4847', '8617', 'z', 'v', 'd', '465', '2165', '189', '2751', '3581', '5413', '5749', '3189']
answer:

a, c, d, f, g, i, j, l, m, o, p, q, u, v, y, z