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:
['5431', 'o', 'u', 'l', 'f', 'd', 'r', '1479', '9357', 's', 'v', '6399', 'b', '7937', 't', '8497', 'r', '131', 'h', 'c', 'v', '8879', 'k', 'r', '4687', 'l', '1065', 'r', 'w', 'l', '3305', '461', 'q', 'h', 'b', 'e', 'e', 'w', '5999']
answer:
b, c, d, e, f, h, k, l, o, q, r, s, t, u, v, w


question:
['d', '1989', '6365', 'y', 'm', '1245', '7539', 'm', '3787', '6987', 'e', 'e', 'y', '9577', 'b', '5', '8179', 'x', '2853', '6337', 'w', 'f', 'b', 'q', '563', '6077', '1133', 'x', '6045']
answer:
b, d, e, f, m, q, w, x, y


question:
['4853', 't', 'p', '2923', '3089', '4757', '8089', '3673']
answer:

p, t