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', 'g', 'q', 'e', '8045', '9999', '9555', '7995', '7195', 'z', 't', '5223', '3699', 'i', '4797', '3817', 'x', 'y', 'w', 'o', '8915', '7803', 'n', '1117', 'c', '9647', 'p', 'e', '9669', '4845', '9255', '4545', '3693', '6871', 'w', '4327', '3285', 'k', 'f', 'x', 'i', 'b', '5967', '6601']
answer:
b, c, e, f, g, i, k, n, o, p, q, t, w, x, y, z


question:
['2819', 'k', 'u', 'a', '4575', 'a', 't', 'a', 'f', '1507', '415', 'w', 'o', 'o']
answer:
a, f, k, o, t, u, w


question:
['n', 'c', 'd', '1403', 't', '99', '6705', 'r', 'n', '1227', 'r', '1859', 'p', 'r', 'a', 'z', 'z', '4567', '789', 'b', '3831', '7959', 'n', 'm', 'k', '8003']
answer:

a, b, c, d, k, m, n, p, r, t, z