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.

[Q]: ['7055', '2573', '1713', 'x', 'm']
[A]: m, x


[Q]: ['8859', '575', 'l', 'e', '6575', '1303', '8643', '1395', '3171']
[A]: e, l


[Q]: ['4339', 'b', 'd', 'z', 'q', 'm', 's', '9331', 'y', 'y', 's', 'd', 'w', '7209', 'e', '8021', '7425', '8589', 't', 'e', '1613', 'n', '6941', 'i', 'g', '1049', 'j', 'j', 'd', '301', '9711', 's', 'a', 'w', 'b', '5263', 'q', 'e', 's', 'd', 'z', 'i', 'd']
[A]:
a, b, d, e, g, i, j, m, n, q, s, t, w, y, z