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: ['a', 'y', 'v', 'f', 'x', 'k', 'f', 'j', '6245', '6289', 'd', '6909', '8701', 'm', '3277', 'f', 'j', 'j', '9227', '8663', '5771', 'j', 'n', 'u', '7837', 's', '2539', '6363', 'g', 'a', '1009', 'v', '1483', 'x', 'i']

SOLUTION: a, d, f, g, i, j, k, m, n, s, u, v, x, y

PROBLEM: ['6709', 't', 'n', 'k', '991', 'a', '8899', '3563', '527', 'm', '4599', '6679', 'm', 'x', 'f', 'o', '3275', 'x', '677', 'b', '3329', '3593', '5183', '5753', 'u', '6045', '2607', 'y', '9873']

SOLUTION: a, b, f, k, m, n, o, t, u, x, y

PROBLEM: ['y', 'g', 'q', '8087', '4245', '573', 'p', '6853', '3525', '8177', 'h', '9569', 'i', 'x', 's', '4065', 'l', 'f', 'o', 'e', '7371', '6685', '8531', 'h', '931', '2251', '6971', 'o', '3393', 'g', 'l']

SOLUTION:
e, f, g, h, i, l, o, p, q, s, x, y