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]: ['o', 'm', '8015', '787', '4787', '1727', 'f', 'e', 'c']
[A]: c, e, f, m, o


[Q]: ['a', 'a', 'b']
[A]: a, b


[Q]: ['i', 'f', 'o', '545', '6805', '6681', 'n', 'z', '2743', '4649', '7575', '499', 'g', '1863', 'z', 'g', 'l', 'b', 'h', '7061', 'm', '529', '5937', 'j', '9737', '773', '3301', 'n', '57', 'j', 'd', 'c', 'u', 'm']
[A]:
b, c, d, f, g, h, i, j, l, m, n, o, u, z