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:
['r', 's', '3409', 'a', 'e', '6855', 'i', 'n', '8655', 's', 't', '8401', 'u', '9603', '8815', 'q', 'a', 'x', 'i', '8455', 'e', '5877', '3917', 'p']
answer:
a, e, i, n, p, q, r, s, t, u, x


question:
['7677', '4069', 'b', 'w', '4381', 'b', '5757', '711', '765', '8347', '6547', '9527', '945', '5333']
answer:
b, w


question:
['o', 'r', 'n', 't', 't', '8559', 'f', '4281', 'j', '8303', '1771', '6953', 'q', '371', '141', 'w']
answer:

f, j, n, o, q, r, t, w