You will be given a definition of a task first, then some input of the task.
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.

['6253', '249', '5435', 'a', '6461', '9701', '7225', '5727', '9139', 'j', 'c', '7393', '7333', '1621', 'u', '8203', 'm', '5071', '1925', '3235', 'k', '8021', 'q', 'w', '7071', 'x', '9631', 'k', 'r', '6599', 'a', 'j', '7171', 'l', '3769', '5667', 'x', 'i']
Output:
a, c, i, j, k, l, m, q, r, u, w, x