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:
['395', '8309', 'v', 'r', 'x', 'j', 'l', 'b', 'c', 'c', '3123', 't', 'a']
answer:
a, b, c, j, l, r, t, v, x


question:
['5711', '8839', '6771', '1203', 'k', 'e', 'p', '3593', 'm', 'm', 'o', 'h', 'm', 'i', '1425', '9897', '7795', 'b', '9665', '5011', '3281', '911', '8169', '7695', '7821', 'm', 'a', '8359', '5839', '1411', 'v', '4471', '7053', '6049', 'o', '7685', 'r', 'k', '761', 't', '5987', 'h']
answer:

a, b, e, h, i, k, m, o, p, r, t, v