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:
['v', '6635', '5395', '3263', '4391', 'h', '1521', 'f', '9861', '6125', '1673', '3679', '8681', '4967', 'f', 'a', 'c', 'k', 'n', '4155', 'e', 'm', 'i', '1699', 'r', 'f', 'u', 'r', '3451', 'v', '7239', 'o', '4359', 'l', 'a', '2925']
answer:
a, c, e, f, h, i, k, l, m, n, o, r, u, v


question:
['t', 'c', 'r', '4459', 'o', '1407', 'x', '1515', '331', 'm', '1535', 'p', 'u', 'g', '2513', 'o', '7827', '8149', 'd', 'z', 'q', '5655', 'x', '9997', '2809', 'g', 'h', '6309', 'a', 'j', '9773', '2115', 't', '9113', 'q', 'o', '427', 's', '3815', '5423', 's', 'n', 'i', 'o', '3643']
answer:
a, c, d, g, h, i, j, m, n, o, p, q, r, s, t, u, x, z


question:
['7807', '8339', 'n', 'n', '2585', 'j', 'f', '2577', '7773', '4633', '5751', 'm', 's', '3413', 'f', 'x', 'g', '7151', '4601', '827', '785', '5761', 'p', 'c', '9269', 'd', 'c', 'k', 'v', '1387', '511', '3861', '2355', 'e']
answer:

c, d, e, f, g, j, k, m, n, p, s, v, x