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:
['i', '9215', 'n', 'p', '4815', '8757', 'm', '1755', 'c', 'z']
answer:
c, i, m, n, p, z


question:
['1799', '6409', '9257', '5923', 'm', 'j', '2565', '715']
answer:
j, m


question:
['g', '8381', 'w', 'p', '3903', 's', '7165', '9507', '8401', 'i', '2593', 'z', 't', 'g', 'k', 'c', 'q', '5905']
answer:

c, g, i, k, p, q, s, t, w, z