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]: ['6737', 'g', '9985', '5257', 'k', 't', '7863', 'y', '8319', 'l', 'o', '6505', '6531', 'z', '3055', '2943', '3625', 'h', '4867']
[A]: g, h, k, l, o, t, y, z


[Q]: ['8105', '8751', '3893', '4477', 'n', 'b']
[A]:
b, n