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:
['v', '5433', 'v', '6749', '7491', 'i', 'm', 'e', '5815', '8423', '833', '7359', 'm', 'i', 'f', 'u', 'p', 'j', 't', '3171', '6165', 'q', 'a', '9475', 'm', 'q', '5995', '8443']
answer:
a, e, f, i, j, m, p, q, t, u, v


question:
['k', '1995', 'b', '2581', 'x', '2639', 'i', '6761', '2701', 'd', '6993', '9375', 'r', 'm', '249', '8115', '8179', 't', '4901', 'i', '6197', '2809', 'e', 's', 'j', '4261', 'f', '6649', '7527', '3839', '5651', '9287', 'n', '2505', 's', 'q', '2825', 'g']
answer:
b, d, e, f, g, i, j, k, m, n, q, r, s, t, x


question:
['f', 'v', 'v', '7303', 'j', 'a', '1943', 'n', '8529', '4905', '2651', 'i', 'q', 'n', '2423', '2791', 'm', '9351', 'o', 's', 'e', '7257', 'j', '1797', '2529', '5205', '7527', 'r', '7835', '443', '5751', 'l', 'w', 'l', '183', 'z', 'f', '6405', '5679', '1313', '9707', 'o', 'r']
answer:

a, e, f, i, j, l, m, n, o, q, r, s, v, w, z