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: ['9273', '5219', 'e', '9413', 'v', 'h', '5657', '797', '2303', '2119', '4791', '2757', '4983', 'h', '9681', '4503', '6657', 't', 'i', 'g', '9375', '9901', 'm', 'y', '6461', 'h', '6663', '9493', '5897', '8829', 'd', 'x', '901', '833', 'u']

SOLUTION: d, e, g, h, i, m, t, u, v, x, y

PROBLEM: ['2741', '2541', '8943', 'l', '4047', '2211', 'p', 'e', 't', '7645', '9771', 'f', '5063', '2303', '6097', '5089', 'd', 'e', '1409', '3125', '2171', 'g', '1247', '4045', 'v', 'h', 'u', '2587', '5207', '5553', 'g', 'd', '6891', 'e', '2471', '2435']

SOLUTION: d, e, f, g, h, l, p, t, u, v

PROBLEM: ['9477', '6761', 'n', '639', 'g', '9793', 'i', 'p', 'z', '2357', 'z', 'u', 'v', 'y', 'k', 'i', 'd', 'n', 'd', 't', 't', 'u', '7111', '1297', '3123', '1607', '3595', 'a', '2845', '4959', 'u', 'w', '501', 'o', '4433', '4753', 'c', '1399', 'l', '3891', '849', '5045', '819']

SOLUTION:
a, c, d, g, i, k, l, n, o, p, t, u, v, w, y, z