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:
['d', '771', '4193', 'e', '1537', 'a', 'q']
answer:
a, d, e, q


question:
['2915', '6033', '5541', '4685', '1263', '6701', 's', '7269', 'g', '8033', '8171', '6917', 'l', '2913', '447', 'g', 'a', 'z', 'o', '7563', '5385', '5259', '5067', '4869', '2653', '6925', '7001', '8553', 'x', '1243', '9131', '5037']
answer:
a, g, l, o, s, x, z


question:
['1035', '5785', '3543', '2171', '9509', '2779', 'l', 'c', 'z', '1517', '6329', 'm', 'a', 'h', 'j', 'm', 'y', '9041', '5711', '7569', '9789', '9039', 't', 'q', '7565', '5847', '2283', 'h', 'p', '3995', '1013', 'v', '8567', 'b']
answer:

a, b, c, h, j, l, m, p, q, t, v, y, z