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:
['7965', '6465', 'c', '7963', 'j', '6839', '9989', '1019', 'x', '1303', '2633', 'y', '6865', 'a', 'k', '635', '3719', '7229', 'k', 't', 'r', '5741', '9569', '4931', '1125', 'f', '5429', 'c', '2065', '6315', 'e', '6877', '2005', 'x', '7831', '7297', 'm', '3571', 'b', '8617', '2981', 'i', '5105', 'g', 'u']
answer:
a, b, c, e, f, g, i, j, k, m, r, t, u, x, y


question:
['4993', '6641', '3127', '9409', '8453', '5909', '6109', 'y', 'f', '6859', 'c', '3863', 't', '1221', '3689', 'w', 'h', '7947', 't', '5979', 'l', 'i', '1321', '3149', 'l', 'v', '3825', 'z', '9297', 'f', 'e', '7205', 'a', 'a', '2645', '391', '4965', 'w', 'h', '7715', '9409', '3603', '4147']
answer:
a, c, e, f, h, i, l, t, v, w, y, z


question:
['9793', '9187', '4255', 'g', '6377', '7079', 'o', 'h', 'e', 'k', 't', 'a', 'm', 'o', 'q', '7691', '5249', '1413', 'r', '1263', 'x', 'r', '4135', '7323', 'i', 'm', '6311', 'l', '7747', 'n', '3715', '8011', '3339', '1401', 's', 'l', '4205', 'o', 'k', 'f']
answer:

a, e, f, g, h, i, k, l, m, n, o, q, r, s, t, x