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:
['f', '9203', 'w', 'f', '3751', '8095', '1319', 'f', '3017', 'r', 'y', '8221', '2715', '9959']
answer:
f, r, w, y


question:
['o', '4169', 'k', '7349', 'w', 't', '8271', '8781', '3725', '2865', '6053', 'j', 'z', '4211', '8231', '213', '6389', 'f', 'h', 'g', '9269', '4617', '4137', 'i', 'y', 'i', 'n', '4597', 'p', 'z', '3195', '3231', 'c', '1901', '1231', 'p', '4509', '2557', '3715']
answer:
c, f, g, h, i, j, k, n, o, p, t, w, y, z


question:
['x', 'w', '7849', '8507', 'p', 'g', '3095', '6733', '6087', '1527', 'w', 'j', 'e', 'x', 'w', 'c', 'h', 'f', 'q', 'f', 'l', '4987', 'g', 'j', 't', '2545', 'b', 's', '9619', '1409', 'a', 's', '6821', 'b', 'b', 'r', 'd', '5205', 'c', 'y']
answer:

a, b, c, d, e, f, g, h, j, l, p, q, r, s, t, w, x, y