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:
['3411', 'a', 'v', 'j', '8925', '909', 'h', 'l', 'r', '1371', 'u', '7789', '4813', 'u', 'q', 'i', '8473', 'n', '7191', 'c', '4641', 'e', '5107', 'q', 'z', 't', '105', 'q']
answer:
a, c, e, h, i, j, l, n, q, r, t, u, v, z


question:
['w', '4335', 'l', '9761', 'f', '1083', 'z', 'k', '1929', '1845', 'g', 'm', 'i', '459', '87', '5797', '4919', 'l', '3597']
answer:

f, g, i, k, l, m, w, z


