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:
['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:
['9483', '501', 'j', 'k', '3103']
answer:
j, k


question:
['1763', '8211', 'm', 'v', 'j', '5045', 'b', '4913', '4407', '8357', '3623', '5441', '8529', '4503', 'b', '2429', 'u', '7401', '9265', '8861', '2369', 'o', 'm', 'h', 'l', 'u', '6937', 'g']
answer:

b, g, h, j, l, m, o, u, v