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.

[Q]: ['815', '6967', '6553', 'r', 'y', '3641', 'q', 'b', '6131', '4289', 'w', '6093', '6055', 'i', 'b', 'y', '5107', 'v', 'g', '9709', 'x', 'i']
[A]: b, g, i, q, r, v, w, x, y


[Q]: ['g', 'p', '2925', 'n', 'o', 'y', '6381', 'l', '4963', 'g', 'm', 'u', 't', '9389', '3787', '7713', '1251', '779', 'i', 'w', '9869', 'y', 'y', '3881', 'k', 't']
[A]: g, i, k, l, m, n, o, p, t, u, w, y


[Q]: ['6717', '7543', 'q', '4999', '3993', '1369', '4701', 'y', '2255', '9033', 'k', 'f', '7011', 's', '5505', '8807', '911', '6871', 'u', 'x', '525', 'm', '453', 'y', 'a', 'f', 'z', 'n']
[A]:
a, f, k, m, n, q, s, u, x, y, z