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: ['7595', '5303', '3985', 'n', 'w', 's', 'r', 'f', '8237', 'q', 'y', 'f', '3121', '2463', '4597', 'q', '6801', 'f', 'i', '8563', '3267', 'k', '6157', 'f']

SOLUTION: f, i, k, n, q, r, s, w, y

PROBLEM: ['i', 's', 'f', 'i', '2293', '245', '4983', 'h', 'h', '6203', '8703', '1613', 'h', 'o', '3635', '8069', '2829', '1939', 'u', 'm', '5305', 'n', 'k', '9367', 'u']

SOLUTION: f, h, i, k, m, n, o, s, u

PROBLEM: ['i', 'v', '4863', 'm', 's', '1159', '6925', 'l', '4201', 'q', '5615', 't', '3909', 's', 'q', 'l', '9195']

SOLUTION:
i, l, m, q, s, t, v