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:
['5345', 'f', '6605', 's', 'q', 'w', 'p', 'o', 's', 'u', 'i', '7339', '8379', 'h', '9547', 'b']
answer:
b, f, h, i, o, p, q, s, u, w


question:
['m', '3809', 'l', 'k', '1929', '7963', 'n', 'u', '2125', 'g', 'o', '8325', 'o', 'h', 'y', '3025', 'e', 'e', 'c', 'x', '8445', '4979', 'z', 'f', '4201', '4765', 'g']
answer:
c, e, f, g, h, k, l, m, n, o, u, x, y, z


question:
['7289', '4837', '1953', 'b', '6405', 'o', 'z', '3821', '3963', '825', 'i', '8697', '5413', 'p', '2619', 'n', '9621', 'k', 'l', 'p', '1751', 'w', '3215', '7723', '4483', 'u', 'l', '3291', '9531', '1137', 'i', '5715', '499', 'n', '2895', '6563', 'r', '1345', '4367', '143', '8971', '6759', '8205', 'z', 'w']
answer:

b, i, k, l, n, o, p, r, u, w, z