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: ['9483', '501', 'j', 'k', '3103']

SOLUTION: j, k

PROBLEM: ['9927', '7043', 'p', '447', 'v', '6567', '3963', '4983', '947', '7765', '3065', 'x', 's', 'a', '2435', 'o', 'j', '2725', '9691', '2999', '1971', '2499', '2291', '4289', 'e', 'z', 'p', 's', '8249', 'f', '405', '4655']

SOLUTION:
a, e, f, j, o, p, s, v, x, z