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.

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

['d', 'a', '6931', 'c', 'u', 'z', '9713', 'v', 'm', 'e', 'k', 'o', '9705', 'a', '5373', 'c', '2983', '8097', 'h', '3039', 'g', 'f', 'n', 'v', '853', '8227', '7573', 'j', 'h', 'k', 'o', 'k', '8897', 'd', 'g', 'd', 'd', '4039']
a, c, d, e, f, g, h, j, k, m, n, o, u, v, z

['p', 'q', '4261', 't', 'k', '3985', '1779']

k, p, q, t