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:
['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:
['477', '3931', 'g', '5967', 'm', '9845', '1607', 'a', '1749', 'k', 'j', '7945', '9125', 'v', 'n', 's', '5185', '1117', '17', 'x', '4149']
answer:
a, g, j, k, m, n, s, v, x


question:
['8447', 'm', 'w', '8645', 'f', 'z', 'y', '7727', '6735', 'd', '805', 'i', 'b', '5303', '8395', 'k', 'o', '6609', '9367']
answer:

b, d, f, i, k, m, o, w, y, z