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:
['t', 'r', '2959', '2517', 'a', '9959', '729', '511', 'y', 'r', '465', 'c', '687', 'm', 'b', 'm', '3449', '9713', 'g', '8275', '8823', 'a', 'z', 'w', '2185', '6283', '8457', '8137', '7163', '8329']
answer:
a, b, c, g, m, r, t, w, y, z


question:
['4925', '9943', '7935', '4387', '2449', '5797', 'i', '1517', 'w', 'e', '9525', 'y', 't', 'e', '2793', 'v', '9897', '8709', '7247', 'o', 'f', '5549', 'q']
answer:
e, f, i, o, q, t, v, w, y


question:
['5227', 'h', 'd', '5531', '7837', '1637', '1903', 'n', 'j', '4175', '1725', 'm', '6841', 'n', '1303', 'w', 'o', 'j', '2553', 'r', 'w', 's', 'v']
answer:

d, h, j, m, n, o, r, s, v, w