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', '3765', '4065', 'a', '4201', 'f', 'x', '9275', 'q', '9303']

SOLUTION: a, f, q, v, x

PROBLEM: ['w', 'g', '1649', 'a', '2115', '6763', 'r', 't', 'l', 's', 'y', '5659', 'a', 'b']

SOLUTION: a, b, g, l, r, s, t, w, y

PROBLEM: ['1095', 'r', '7187', 'i', 'b', 'b', '8747', '7149', '6327', 't', 'm', 'a', 'r', '6531', '9891', 'd', '9393', '4099', 'a', '7819', 'o', '5801', 't', 'y', 'w', 'p', '5817', '1973', 'q', '7893']

SOLUTION:
a, b, d, i, m, o, p, q, r, t, w, y