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:
['2527', '9123', '8717']
answer:
-1


question:
['477', '3931', 'g', '5967', 'm', '9845', '1607', 'a', '1749', 'k', 'j', '7945', '9125', 'v', 'n', 's', '5185', '1117', '17', 'x', '4149']
answer:
a, g, j, k, m, n, s, v, x


question:
['d', 'm', 'x', 'b', '6751', '8429', '5543', '3831', '3221', 'p', '8211', 'e', '1939', 'r', 'j', '8293', 'b', 'c', 'y', '2723', 'w', '2365', 's', '2527', 'm', '9041', '1041', 'd', '3011', '2767', '3527', '4789', 'i', 'm', 'q', 'v', 'b']
answer:

b, c, d, e, i, j, m, p, q, r, s, v, w, x, y