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:
['g', 'u', 'q', '1375', '9491', 't', 'w', 'c', 'v', 'y', '3169', '1607']
answer:
c, g, q, t, u, v, w, y


question:
['y', '8115', 'f', '5333', 'f', '3437', 'b', 'e', '5719', 'm', 'w', '95', '4863', 'k', '4895', 'a', '8179', 'm', '7919', '1731', '229', 'r', '1847', '7559', '6669']
answer:
a, b, e, f, k, m, r, w, y


question:
['4925', 'i', 'q', 'k', '7615', 'r', '7217', 'o', '8097', '9151']
answer:

i, k, o, q, r