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:
['315', '9975', '3013', 's', '6131', 'e', 'e', 'u', 'a', '1729', 'g', 't', 'y', 'f', '7523', 'e', 'g', '489', 'm', 'p', 'f', 'e', '2077', 'e', 'g', 'c', 'l', '6389', 'k', 'b']
answer:
a, b, c, e, f, g, k, l, m, p, s, t, u, y


question:
['5159', '6407', '4021', '6655', 'c', 'k', 'w', '7191', 'l', '4321', '1609', 'm', '1991', '9261', '511', 'p', '7495', 'b', 'e', '4647', '2711', 'd', 'y', '3835', '5037', '3613', '2695', '3367', 'm', 'j', 'y', '9561', '4889', 'a', 'z', '2253', 'p', 't', 's', '8371', '2859', 's']
answer:
a, b, c, d, e, j, k, l, m, p, s, t, w, y, z


question:
['7323', 't', 'l', 'z', 'e', '7461', '767', 'o', '9151', '8233', '7313', '1827', '6797', '3943', 'n', 'q', 'p', '9249', 'y', '4963', 'c', 'h']
answer:

c, e, h, l, n, o, p, q, t, y, z