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:
['7155', 'y', '145', '7147', 'u', '8453', 'd', '3693', '6471', '5289', 'n', 'p', '8289', '2929', '199', 'e', '8377', '8937', '5315', 't', 'l', '7715', 'c', 'y', 'f', '9999', 'p', '3655', '5489', 'q', '2321', '9881', '2265', 'n', 'v', '455']
answer:
c, d, e, f, l, n, p, q, t, u, v, y


question:
['2293', 'p', '9787', '7241', '8689', 'u', '3141', 'h', 'c', 'b', 'f', 's', '319', 'c', 'p', '6909', 'p', 'f', '1717', 'd', '2285', 's']
answer:
b, c, d, f, h, p, s, u


question:
['l', 'f', '7607', 'j', 'w', '9439', '4009', 'l', 'f', 'i', '2547', '4605', '8315', 'k', 'h', '4649', 'y', '5811', 'g', '7031', 'p', 'c', 'a', '5557', 't', 'w', '7361', '8311', '2593', 'i', 'v', '581', 'h', 'e', '5103', '6973', '4323', '5873', 'c', 'd']
answer:

a, c, d, e, f, g, h, i, j, k, l, p, t, v, w, y