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:
['d', 'r', '7769', '2159', 's', '3269', '5527', 'l', 'z', 'e', '5165', 'x', 'x', '8273', 'g', 'm', '7609', '4015', '6403', '3753', 'y', 'h', 'l', 'i', '389', 'm', 'u', '6845', 'r', 'c', '7571', '3355', '9755', 'n', '4625', 'p', '5645', '1703', '4439', 't', '8431']
answer:
c, d, e, g, h, i, l, m, n, p, r, s, t, u, x, y, z


question:
['w', 'a', 'm', 'd', '409', 'm', 'v', 's', '7801', 'l', '8551', 'k', '867', 'n', '7731', 'z', '3773', '9137', 'v', 's', 'p', 'p', 'f', 'z', 'g', 'q', 'g', '877', '697', '2057', '8389', '2399', '5263', '2761', '9841', '1781', 'l', '8023']
answer:
a, d, f, g, k, l, m, n, p, q, s, v, w, z


question:
['t', '1397', 'k', 'v', '4703', '9093', 'h', '5791', 'g', '2259', 'v', '989', '1841', 'g', '3129', 'a', 'f', 'l', 'n', '2585', 'c', 'r', '7925', 's', '1743', 'z', '3397', 's', 'p', 'a', 'l', '185', 'j', '6955', 'u', 'd', 'h', '4915', 'k', '6047', '9067', 'k', '5507']
answer:

a, c, d, f, g, h, j, k, l, n, p, r, s, t, u, v, z