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:
['s', '6723', 'l', '1573', '1129', 'n', '4277', '5003', 'y', '7563', 'c', '6747', '3105', 's', '3593', '8417', '8253', '4157', 'w', 'f', 'z', 'd', '9685', '1033', 'h', '4893', 't', 'j', '6821', 'z', 'a', 'u', '591', 'o', '1087', '2147', '1223', '2339', 'i', 'y', '9307', 'x', 'z', 'r', 'y']
answer:
a, c, d, f, h, i, j, l, n, o, r, s, t, u, w, x, y, z


question:
['s', 'c', 'e', '2457', '9413', 'r', '9949', 's', 'z', 'e', 'a', 'o', '7207']
answer:
a, c, e, o, r, s, z


question:
['4923', 'q', '9791', 'l', 'o', '1691', 'v', '2717', '6295', '5761', '7731', '1827', '31', '6853', 'k', '9419', '349', 's', 'f', '5895', '6211', '5611', '2919', 'a', 'e', 'k', 'y', '6213', '2047', '5679', 'f', '6459', '1481', 'a', 'y', '6065']
answer:

a, e, f, k, l, o, q, s, v, y


