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:
['n', 'y', '7087', '9539', 'x', 'i', 'w', '7237', '8613', 'k', '5999', '4179', 'o', 'm', '7485', '1955', 'w', '1451', 'h']
answer:
h, i, k, m, n, o, w, x, y


question:
['8319', 'f', 'w', 'w', 'v', '6521', '4503', 'b', 's', 'b', '9651', 'k', '4635', '2195', '7537', '6839', 'i', 'd', 'b', '205', 'q', '7333', 'q', '5129', '4921', 's']
answer:
b, d, f, i, k, q, s, v, w


question:
['9209', '575', '6527', 'o', 'c', 'x', '2499', 'r', 's', '8549', 'q', '8535', '4691', 'q', '8849', 'g', 'i', '1203', '463', 'z', '1621', '9099', 'h', '9741']
answer:

c, g, h, i, o, q, r, s, x, z