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:
['5039', '2227', 't', 'o', '3313', 'm', 'v', '637', '6773', 'v', 'c', 'l', 'y', 'u', '3823', '9669', 'k', 'h', '3589', 'b', 'i', '3833', 's', 'm', '8201', 'u', '3143', 'k', '4111', '9769', '425', '4339', '209', 'c', 'c', '669', '8201', 'u', '7443', '2387', '6919', 'b', 'b', '2873']
answer:
b, c, h, i, k, l, m, o, s, t, u, v, y


question:
['2799', '7519', '345', 'e', 'l', '9369', '4703', '4111']
answer:
e, l


question:
['c', 'p', '6489', '6721', '5859', 't', '4391', '1219', 'c', '4239', '3751', '9397', '6269', 'c', '6493', 'm', 'q', '9275', '2295', 'n', 'o', '2305']
answer:

c, m, n, o, p, q, t


