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:
['163', 'x', 'g', '5997', 'm', 'l', '7225', '7907', '375', 'y', 'a', 'j', 'c', 'j', '7755', '147', 'h', '3845', 'y', 's', 'h', 'u', '8737', '6091', 'j', 'f', 'c', '7395', '881', '1771', 'y', '3691', 'h']
answer:
a, c, f, g, h, j, l, m, s, u, x, y

question:
['h', '6865', '4019', '8571', 'y', '5575', '7835', '9537', 'n', '875', 't', 'a', 's', '2769', 'p', '1607', 'n', '4087', '961', '7869', '5085', '2131', '4867', 'j', 'h', 'y', '3105', '6609', 's', 'l', '3399', '5013']
answer:
a, h, j, l, n, p, s, t, y

question:
['4885', 'k', '6215', '8553', 'i', 'u', 'l', 't', 'q', '2977', '9237', 's', 'r', '7205', 'b', '5685', 'f', '631', '709', '1319', 'd', 'c', '9053', '9395', 'q', '843', '8547', 'w', 'k', 'y', 'y', '9821', 'k', 'n', '1367', '4657', 'c', '319', '2617', '4303', 'x', 'd', 'm', '3739', '5079']
answer:
b, c, d, f, i, k, l, m, n, q, r, s, t, u, w, x, y