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:
['z', 'l', '1759', 'k', '8197', 'v', '931', '2587', '7219', '3455', 'e', '8135', 'm', 'n', 'm']
answer:
e, k, l, m, n, v, z


question:
['2161', '8009', '3057', 'r', '3897', 'd', 'j', '2727', 'b', '3231', 'i', '9227', '393', '5799']
answer:
b, d, i, j, r


question:
['7061', '9869', 'u', '7151', 'j', 'g', 'x', 'd', 'p', 'u', '1671', '6593', '5813', 'u', 'g', 'a', 'm', '9213', '1031', '4205', 'p', 'u', 'v', '255', 'g', 'c', '6347', '959', '8645']
answer:

a, c, d, g, j, m, p, u, v, x