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:
['c', 'e', '6509', '1295', 'u', '5445', '1731', '3049']
answer:
c, e, u


question:
['c', '6027', 'o', 'h', 'l', '7893', 'u', 'f', '7661', '4715', '1373', '4799', 'd', 'z', '411', '4753', 'd', '8241', '1589', '4173', '3921', 'j', 'o', '5067', '8879', 'e', 'm', '9543', '9625', '855', 'u', 'd', '5859', '4243', '5747', '5147', '7315', 'd', 'x', 'q', '7841', '7397', 'm']
answer:
c, d, e, f, h, j, l, m, o, q, u, x, z


question:
['1859', 'r', 'c', 'x', '8867', '4205', '1037', '4763', 'n', '7447', 'h', 'j', 'h', '4077', '3473', '8341', 'j', '3081', '6723', '3877', '5787']
answer:

c, h, j, n, r, x