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: ['v', 'l', 'v', '7673', '8975', 'u', '2471', '4151', '3615', '1139', 'i', 'z', '8833', 'v', '341', 'l', 'n', 'l', 'd', '9207', '1861', '3901', 'a']

SOLUTION: a, d, i, l, n, u, v, z

PROBLEM: ['o', '4167', 'b', '1651', '8327', '9219', 'o', 'v', '5841', '6057', 'i', 'q', 'o', 'r', 'a', '7069', 'y', 'h', 'd', '3775', 'j', 't', '3663', '55', '7117', 'e', 'u', 'm', '931', '5777', '8773', '4891']

SOLUTION: a, b, d, e, h, i, j, m, o, q, r, t, u, v, y

PROBLEM: ['5513', '197', 'f', '275', 'p', 'q', '6249', 'g', '9355', 's', 'h', 'g', '1997', 'k', '2649', 'u', '9261', '2545', 'm', 'i', '913', 'o', '2927', '7073', '8101', 'r', '4157', '5315', '8027', '8393', '795', '3045', '6339', 'c', '489', 'm', 's', 't', '813', 's', 'e', 'd', '4933', 'n', 'd']

SOLUTION:
c, d, e, f, g, h, i, k, m, n, o, p, q, r, s, t, u