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:
['j', 'y', '9907', 'a', '5715', 'l', '9817', '1949', '2697', '2255', '9571', '8957', '9329', '6055', 'z', 'q', '1185', '4593']
answer:
a, j, l, q, y, z


question:
['l', '6819', '1029', '2925', '2361', '5545', '2151', '2681', 'f', 'p', '1263', '2875', 'b', '4665', 'f', 'g', 'p', '4829', '8453', 'z', 'l', '4219', '7517', '25', 'a', '5099', '3693', 'i', '1815', '1541', 'g', '7665']
answer:
a, b, f, g, i, l, p, z


question:
['j', '7219', '8485', '7331', '5861', 'k', 'i', '4719', 'q', 'a', 'w', 'b', 'u', 'u', '8693', '2709', 'x', '6963', '6961', '409', 'p', '5919', 'f', '969', 'v', 't', 'n', '8323', '9317', 'c', '3165', 'j']
answer:

a, b, c, f, i, j, k, n, p, q, t, u, v, w, x