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.

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

[EX Q]: ['1595', '2915', 'o', 't', 'c', 'h', '3969', '5407']
[EX A]: c, h, o, t

[EX Q]: ['x', 'a', 't', 'n']
[EX A]:
a, n, t, x