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:
['1749', 'i', 'w', 'j', '3171', '1999', '1037', '4937', '7013', '3593', '287', 'o', 'i', 'j']
answer:
i, j, o, w


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:
['z', 'h', 'p', 'x', 'w', '973', 'r', 'x', '8901', 'l', 'i', 'p', '6597', '9199', 'r', '9607', 'c', '2603', '6703', '7471', 'p', 'l', 'o', 'p', 'n', 'm', 'g', '2601', '9751', 'm', '2645', '9439', '1373', 'e', '7753']
answer:

c, e, g, h, i, l, m, n, o, p, r, w, x, z