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:
['9925', 'f', '6149', 's', 'd', 's', '75', '8577', '2319', 'b', '3769', '5211', 'q', 'm', '8127', 'f', '3801']
answer:
b, d, f, m, q, s


question:
['9273', '5219', 'e', '9413', 'v', 'h', '5657', '797', '2303', '2119', '4791', '2757', '4983', 'h', '9681', '4503', '6657', 't', 'i', 'g', '9375', '9901', 'm', 'y', '6461', 'h', '6663', '9493', '5897', '8829', 'd', 'x', '901', '833', 'u']
answer:
d, e, g, h, i, m, t, u, v, x, y


question:
['h', 'k', '6457', '925', 'b', 'g', '203', '4691', 'p', 'e', '6593', 'l', '7249', 'j']
answer:

b, e, g, h, j, k, l, p