instruction:
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.
question:
['8451', 'x', '9965', '9303', 'm', 'f', '4205', 'y', 'n', '8521', '9995', 'z', 's', '3519', 'k', 'e', 'o', 'k', '9611', 'q', 'l', 'p', '3339', '4023', 'n', 'd', '8903', 'a', 'k', 'u', '4009', 'e', 'm', '989', '4495']
answer:
a, d, e, f, k, l, m, n, o, p, q, s, u, x, y, z


question:
['575', 'u', 'c', '8113', '2853', '3661', '9427', '3071', '4069', '835', 'w', 't', 'w', 't', 'v', 'g', 'c', '5497', '1703', '8433', 'g', '3545', '2887', 'z', 'a', '2241', '5799', '5915', 'u', '4015', '8327', 'z', 'a', 'w', '8311', '289', '8575', 't', 'b', '2873', 'r', 'z', 'x', '1165', '9881']
answer:
a, b, c, g, r, t, u, v, w, x, z


question:
['b', '1651', '4975', 'r', 's', 'c', 's', 'q', '6437', '729', 's', 'y', '8347', 'f', 's', '9757', 'v', 'j', 'o', 'g', '2207', 'r', 't', '9377', 'p', 'a', '4121', 'c', '3049', '9039', 'x', 'r', '6459', 'o']
answer:

a, b, c, f, g, j, o, p, q, r, s, t, v, x, y