Given the task definition and input, reply with output. 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.

['s', 'q', 'f', '1059', '7047', 'i', '899', '8673', '77', 'm', '9861', '4235', '1819', '4213', '2425', '4463', '4271']

f, i, m, q, s