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:
['2393', 'c', '4413', '5529', '1487', '2499', 'i', 's', 'i', '8575', 'm', 'z', '7179', '6637', '9181', 'z', 'h', '2487', 'i', '3779', '2017', '5217', '5013']
answer:
c, h, i, m, s, z


question:
['p', '6123', '6961', 't', 'p', 'h', '9035', 'r', '6341', 'x', '3635', '5885', 't', '3543', '9567', '1787', 'o', '2991', 'k', '3441', '4091', 'a', 'r', '423', '9383', '7147', 'h', '663', 'd']
answer:
a, d, h, k, o, p, r, t, x


question:
['4657', 'n', '8891', '4261', '5695', '4861', 'f', 'k', 'l', 'g', '8163', 'c', 'b', 'p', 's', 'i', '8733', 'w', 'w', 'f', 'm', 'f', 'w', 'c', '6561', '5083', 'l', '7919', '3127', '9873', '2079']
answer:

b, c, f, g, i, k, l, m, n, p, s, w