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]: ['6955', '721', '2763', '8121', '9109', '6341', 'p', 't', 'x', '6963', '1137', 'z', 'u', '1949', '7029', 't', '9539', 'a', 'u', '1873']
[A]: a, p, t, u, x, z


[Q]: ['3127', '9253', '5667', '9453']
[A]: -1


[Q]: ['r', '3727', 't', '2525', '559', 'f', 'i', 'b', 'd', '5209', '9077', 'g', '4601', 's', '207', '8363', '1651', 'z', 'o', '9387', '5339', 'i', 'h', '9281', 'n', 'a', '1397', 'm', '6743', 'z']
[A]:
a, b, d, f, g, h, i, m, n, o, r, s, t, z