TASK DEFINITION: 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.
PROBLEM: ['p', '2923', 'e', 'k', '5433', '605', '5079', 'k', 'p', 'x', '4845', '4099', '6795']

SOLUTION: e, k, p, x

PROBLEM: ['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']

SOLUTION: a, e, f, i, j, m, p, q, t, u, v

PROBLEM: ['8627', 'e', 'v', '9475', '4871', '6075', 'f', '5283', '1905', '3917', '5113', 'q', 'y', 'e', '3891', '4587', '9971', '2851', '5853', 'y', '9395', '3763', '1353', '1773', '5631', '1799', '7359', 'x', '1871', 'b', '3283', 'q', 'c', 'j', '3859', 'i', '9723']

SOLUTION:
b, c, e, f, i, j, q, v, x, y