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:
['1931', 'c', 's', '8767', 'z', '8977', '9249', '365', 'p', '7187', 'p', '961', 'k', 'k', '423', '5999', '4697', '6251', '6441', '1821', 's', 's', 'f', '5365', 'z', '5113', 'y', 'k', 'i', '5627', 'u', 'w', '4103', '8035', '7105', 'o', 'n', 's', 'y']
answer:
c, f, i, k, n, o, p, s, u, w, y, z


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:
['9455', 'i', '8175', 'm', 'p', 'r', 'w', '6975', 'm', '4335', '4319', '9899', 'v', 'j', 'c', 'c', 'x', '5689', 'm', 'n', 'f', '4373', 'c', '5997', 'x', 'c', 'c', '6487', '7387', 'e']
answer:

c, e, f, i, j, m, n, p, r, v, w, x