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:
['e', 'n', 'y', 'f', 'l', 'h', '455', 'y', '591', 'm', '9041', 'b', 'b', 'o', '4215', '5009', 'o', 'a', '4369', 'u', '6911', '4825', 't', 'k', '6063', '2939']
answer:
a, b, e, f, h, k, l, m, n, o, t, u, y


question:
['9579', 'm', 'v', 'r']
answer:
m, r, v


question:
['k', '9829', 'b', '5269', '763', 'k', '937', 'u', '1977', '9171', '2627', '2469', '1683', 's', '71', '2911', '8147', 'v', '2157', 'k', '4091', '6077', 'c', '9725', '7849', '2145', '7927', '2831', 'h', 'u', '8427', '281', 'r', '4175', 'k', '3067', 'e']
answer:

b, c, e, h, k, r, s, u, v