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: ['u', '4021', 'u', 'd', 'j', 'p', 'i', 'z', '3223', 'f', 's', 'l', 'p', 'd', '5031', '1059', '7875', '2097', 'q', 'i', '8813', '2017', 'h', 'l', 'y', '57', '1561', 'f', 'j', 'z', '1901', 'u', 'j', 'x', '6561', '9239', '3333', '8793', '4915', '5821', 'h', 'f', '765', 'x']

SOLUTION: d, f, h, i, j, l, p, q, s, u, x, y, z

PROBLEM: ['7417', '2597', '2633', '7721', 'v', 'l', 'p', '4389', 'l', '3965', '6279', 'm', 'v', 'o', 'd', 'o', 'h', 'd', 'r', 'e', '8993', '2711', 'o', 'q', '1399', 'i']

SOLUTION: d, e, h, i, l, m, o, p, q, r, v

PROBLEM: ['8223', '5369', '5345', 'j', '7675', '7135', '4289', 'p', 'q', 'h', 'd', '2851', '1159', '3409', 'a', 't', '2077', '7729', '9429', '5633', 'r', 'b', 'p', '3171', '7505', 'u', 'f', '5653', 'i', 'l', '8637', 'm', 'e', '4931', 'd', '2137', '9239', '3707', '5381', 'a', 'g', '5379', '6707']

SOLUTION:
a, b, d, e, f, g, h, i, j, l, m, p, q, r, t, u