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.

['2329', 'i']
i

['887', 'p', '3819', '2727', '1407', 'b', 'n', '737', 'd', 'w', 'q', '6877']
b, d, n, p, q, w

['m', 'u', 'm', '2527', 'q', '3815', 'g', 'l', 's', '6861', 'l', '4599', 'v', '1247', 'k', 'c', 'n', '4265']

c, g, k, l, m, n, q, s, u, v