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]: ['l', 'g', 'd', 'p', '8163', '6643', 'o', 'p', 'm']
[A]: d, g, l, m, o, p


[Q]: ['1799', '6409', '9257', '5923', 'm', 'j', '2565', '715']
[A]: j, m


[Q]: ['7519', 'v']
[A]:
v