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:
['1945', 't', '4477', '4439', '6569', '2021', 'y', 't', '2725', '8947', '6921', '1373', '8107', 'g', 'c', 'w', 'x', 'b', '9117', 'k', '6567', '5073', '2307', 'e', 'b', '7405', 'e', 'x', '1419', 'd', 'o', 'n', 'a', '2647', 'z', '1459', 'n', '6137', 'u', 'b', 'q', '4459']
answer:
a, b, c, d, e, g, k, n, o, q, t, u, w, x, y, z


question:
['e', '2239', 'l', '8309', 'i', '2613', 'i', '611', '6481', 'j', 'v', '1867', '415', '269', '8053', '3369', 'q', 't', '2303', '7729', '1059', '6135', '3299', 'd', '6855', '207', '6227', '7859']
answer:
d, e, i, j, l, q, t, v


question:
['5509', 'h', 'd', 'n', '8373', 's', 's', '3163', '5491', 'k', 's', '5667', '205', '5297', '77', '6437', '9425', '595', '8287', '7961', 'm', 'o', '8597', 'i', '983', '8621', 'l', 'd', '2797', '7391', '4709', 'f', 'a', '279', 'r', 'u', '3785']
answer:

a, d, f, h, i, k, l, m, n, o, r, s, u