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.

['4885', '6287', '6965', '3527', '453', '4515', 'd', 't', '457', 'l', 'x', 'i', '5757', 'g', '4589', 'r', '145', '6249', 'n', 'm', '1475']
d, g, i, l, m, n, r, t, x