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.

['c', '7039', 'g', '1899', 'r', '507', 'c', '2587', '3865', '1729', '3927', 'r', '3535', '2791', 'm', 'l', 'r']
c, g, l, m, r

['2995', '8179', '8131', '5655', 'j', 'q', 'l', '3193', '1823', 'y', 'n', '7645', 's', '5665', 'r']
j, l, n, q, r, s, y

['o', 'o', '4065', 'c', '595', 'w', '1423', 'l', 'y', 'z', '8331', '8687', '4881', 'b', '805', '3735', '8577', 'd', '797']

b, c, d, l, o, w, y, z