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:
['p', '2923', 'e', 'k', '5433', '605', '5079', 'k', 'p', 'x', '4845', '4099', '6795']
answer:
e, k, p, x


question:
['135', 'u', '3435', '2985', '9811', 'y', '4309', '9757', '905', 'd', 'g', 'q', '1457', 'l', 'o', 'u', '4517', '2333', '3327', '577', 'a', '4041', '8101', '6211', 'f', 'j', '1721', '7217', 'q', '7443', '8477', '3117', '7779', '9339', '8615', 'm', 'c', 'f', 'c', '8979', '7895', 'k', 'w', '1619']
answer:
a, c, d, f, g, j, k, l, m, o, q, u, w, y


question:
['6035', '3623', '5479', 't', '4507', '6265', 'q', 'n', '3627', '5177', '3101', 'u', '6893', '6119', '8399', '9345', '4399', '5341', '1783', '4837', 'i', 'v', '2077', 'p', '6345', 'i', '2967', 'w', '4889', '2403', '8289', 'n', 'o', '293', '6815', 'f', 'y', '4461']
answer:

f, i, n, o, p, q, t, u, v, w, y


