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:
['u', 'o', 'b', 'b', '5873', 'w', 'v', '4171', '7957', '3501', '2563', 'l', 'q']
answer:
b, l, o, q, u, v, w


question:
['5293', '2211', 'r', 'j', 'x', 'y', 'u', 'n', 'r', 'l', 'v', '113', 'v', 'e', '1323', '6291', 'a', '7417', 'j', '4175', 'd', '855', 'z', '1123']
answer:
a, d, e, j, l, n, r, u, v, x, y, z


question:
['e', '7307', '9893', 'd', 'v', '9627', '2927', 'p', 'c', 'j', '2703', '695', 'q', '3687', 't', '5227', '929', '6059', 'v', '3593', 'q', '5753', 'z', '1247', 'g', '4621', '2311', 't', 'x', 'x', '6441', '1971', 'p', 'x', '4329', 'r']
answer:

c, d, e, g, j, p, q, r, t, v, x, z