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:
['p', 'p', '7899', 'u', '971', '7289', 't', '5217', 'k', 'z', 'y', 'y', '6905', '9499', '4085', 'x', '955', 'v', 'j', '9049', '7927', '1757', '193', '2181']
answer:
j, k, p, t, u, v, x, y, z


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:
['2369', '1879', 'm', 'n', 'a', '2819', 'y', '1893', '5697', 'r', '9713', 'a', 'q', '9637', 'i', '5131', '3401', '3225', 'i', '7991', 'f', 't', '7365', 'j', '513', 'u', '1845', 'd', '6015', '6367', 'e', '1709', '5011', 'b', '9633', '2963', 'c', 'x', '4105', 'a', 'i']
answer:

a, b, c, d, e, f, i, j, m, n, q, r, t, u, x, y