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:
['747', '5385', '5313', 'p', '9581', 'r', '1339', '3919', 'e', 'e', '8057', '7739', 'i', 'e', '3311', '963', 'g', 'h', '7349', 'y', '1493', 'e', '3055']
answer:
e, g, h, i, p, r, y


question:
['9403', '9881', '8391', 't', '1793', 'w', 'x', 'y', '6383', 'j', 'r', '5323', 'r', 'l', 'e', 'u', '7193', '2309', '837', 'z', 'w', 'n', '4427', '8269', '6333', 'a', 'p', '1933', '8497', '2665', '1349', '6807', '9009', 'b']
answer:
a, b, e, j, l, n, p, r, t, u, w, x, y, z


question:
['1297', '8999', 'm', 'z', 't', 'x', 's', '8581', '4927', 'w', '5401', 'c', 'q', 'g', '3239', '527', 'y', '719', '7111', 'g', '4079', 'b', '1907', 'a', '1137', 'w', '741', 'k', 'c', 'j', '4783', 'b', 'o', 'i', 'x', 'l', '3663', 'u', '8121', '977', 'z', '6811', '6229']
answer:

a, b, c, g, i, j, k, l, m, o, q, s, t, u, w, x, y, z