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:
['r', 'y', 'c', '3211', '9245', '8459', '8521', '5781', 'w', 's', 'd', '5299', 'a', 'y', 'g', 'm', '6435', '8605', 'e', 'h', '6871', 's', '387', 'l', '5829', 'e', 'd', '9545', '2945', 'k', 'v', 't', '8449', '2199', 'm', '2599', '1489', '6623', 'x', 'l']
answer:
a, c, d, e, g, h, k, l, m, r, s, t, v, w, x, y


question:
['a', '2579', 'f', '6787', '123', '225', '6499', '4419', 'o', '1785', '7981', 'z', 'b', '2441', '2821', 'o', 'k', '2747', 's', 'u', 'q', '3901', '7629', 'k', 'm', 'q', '6577']
answer:
a, b, f, k, m, o, q, s, u, z


question:
['3405', '5757', '8747', '4351']
answer:

-1


