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:
['9579', 'm', 'v', 'r']
answer:
m, r, v


question:
['8451', 'x', '9965', '9303', 'm', 'f', '4205', 'y', 'n', '8521', '9995', 'z', 's', '3519', 'k', 'e', 'o', 'k', '9611', 'q', 'l', 'p', '3339', '4023', 'n', 'd', '8903', 'a', 'k', 'u', '4009', 'e', 'm', '989', '4495']
answer:
a, d, e, f, k, l, m, n, o, p, q, s, u, x, y, z


question:
['x', '5605', '3443', '6793', '5403', '4763', 'v', '3485', '4063', 'w', '419', 'c', 'o', '3827', '7169', '8455', 'j', '6141', '7373', '2181', '157', '7577', 'c', '935', '6017', '4553', '6379', '8049', 'j', '7133', 'v', 'd', 's', '8699']
answer:

c, d, j, o, s, v, w, x