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:
['1595', '2915', 'o', 't', 'c', 'h', '3969', '5407']
answer:
c, h, o, t


question:
['8495', 'p', 'j', 'm', 'n', '9115', '1183', 'r', 'r', '8735', 'a', 'i', 'k', 'p', '8927', 'r', '9283', '9563', 'g', '2503', 'h', '1091', '5257', 'a', '3061', '2835', 'l', 'w', 'j', '7617', '8793', '7463', 'h', '8467', '7337', 'b', '4655', 'd']
answer:
a, b, d, g, h, i, j, k, l, m, n, p, r, w


question:
['7389', 'z', 't', 'm', 'n', 'i', '8071', '6105', 'n', '6907', 'p', 'l', '7177', '8707', 'n', 'q', 's', 'f', 'r', '4067', 'k', '2825', 'y', 'c', '2773', 'r', '9425', '8481', '239', 'i', 'f', 's', 'e', '5745', 'x', 'j', '1741', 'p', '745', '8693', '4581']
answer:

c, e, f, i, j, k, l, m, n, p, q, r, s, t, x, y, z