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:
['1983', '1835', '6543', '6399', '4177', '9385', '7127', 'p', 'l', 'u', 'g', 't', '3423', 'g', 'b', 'l', '3133', '2429']
answer:
b, g, l, p, t, u


question:
['135', 'u', '3435', '2985', '9811', 'y', '4309', '9757', '905', 'd', 'g', 'q', '1457', 'l', 'o', 'u', '4517', '2333', '3327', '577', 'a', '4041', '8101', '6211', 'f', 'j', '1721', '7217', 'q', '7443', '8477', '3117', '7779', '9339', '8615', 'm', 'c', 'f', 'c', '8979', '7895', 'k', 'w', '1619']
answer:
a, c, d, f, g, j, k, l, m, o, q, u, w, y


question:
['e', '2327', 'b', '3787', 'a', '8985', '8329', '2959', '4211', '3759', '2109', '2933', 'n', '3073', 'o']
answer:

a, b, e, n, o