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:
['5011', 'l', '925', 'e', 'b', '3077', 'm', '4541', '781']
answer:
b, e, l, m


question:
['7823', '2933', 'k', '4139', '5585', 'f', 'c', 'm', '2035', 'q', 'z', 'l', '1999', 'q', 'p', '7291', '2091', 'v', '423', 'e', 's', '6089', '4763', '6739']
answer:
c, e, f, k, l, m, p, q, s, v, z


question:
['e', 'j', 'x', '4471', '5299', 'b', 'f', 'n', '4055', '5203', 'r', 'k', 'c', '6973', 'p', '1887', 'l', 't', 'q', 'n', 'h', 'h', '4431', 'a', '5637', '3703', '6599', '9119', '9145', '211', 's', 'v', 'p', 'b', 'm', '637', 'j', '8005']
answer:

a, b, c, e, f, h, j, k, l, m, n, p, q, r, s, t, v, x