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

['k', '6595', '1595', 'v', 'h', 'b', '8815', '6681', 'j', '7581', 'p', '9095', '5453', 'r', 'y', '7755', 'x', '1853', 'k', 'q', 'u', 'j', 'q', '9651', 'o']
b, h, j, k, o, p, q, r, u, v, x, y

['b', 'q', '4561', '3185', 'z', 'i', '2543', '8791', 'l', 'a', '6439', '1143', 'c', '9401', '635', '5955', 'i', 'h', 'h', 't', 'o', 'g', 'p', 'b', '4595', 'u']

a, b, c, g, h, i, l, o, p, q, t, u, z