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:
['3611', '6825', 'j', 'e', 'r', 'a', '8889', 'y', 'x', 'k', '2651', '4545', '2289', 'r', 'q', '3163', 'a', 'i', 'j', 't', 'b', '2673', '4307', 'q', '5839', 'w', 'g', '6221', 'g', 'h', 'h', '5815', 'n', '3551', '7709', 'z', '2281', '7987', 'w', 'a', '2319', '3337', '3409']
answer:
a, b, e, g, h, i, j, k, n, q, r, t, w, x, y, z


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:
['7389', '6203', 'm', '6255', 'a', '2385', 't', '2349', '1507', 'j', 'o', 'a', 'g', '7923', '9177', 'r', '5955', 'k', 'p', '8607', '8203', '9069', '7959', 'i', 'q', '9075', '357', 'e', '783', 'u', '6489', 'o', 'c', 'z', 'i', '813', '1213', 'i']
answer:

a, c, e, g, i, j, k, m, o, p, q, r, t, u, z