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:
['u', '4731', 'l', 'p', '1997', '601', 'n', 'l', 'p', '211', '7355', '6537', 'w', 'x', '1741', '8145', '3689', 'm', 'y', '6945']
answer:
l, m, n, p, u, w, x, y


question:
['w', '1081', 'n', '2073', 't', '6351', '5591', 'a', '113', 'w', 'q']
answer:
a, n, q, t, w


question:
['i', 'j', 'n', '5003', '3719', 'u', 'k', '7825', 'd', '2527', 'u', '3845', '6365', '9071', 'c', '6099', 'i', '419', 'c', '4683']
answer:

c, d, i, j, k, n, u