Instructions: 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.
Input: ['s', 'm', 'u', '8061', '1971', '2451', 's', '3703', '9797', 'n', '6245', 'x', '6979', 'k', 'x', '3297', '3691', 'w', 'i', 'l', '4391', '8321', 'p', 'q', 'k', '3633', 'e', '9875', 'u', '3905', '9233', 'k', '5027', 'm', 'w', 'e', '1325']
Output:
e, i, k, l, m, n, p, q, s, u, w, x