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: ['4925', 'i', 'q', 'k', '7615', 'r', '7217', 'o', '8097', '9151']

SOLUTION: i, k, o, q, r

PROBLEM: ['x', 'i', 'k', 'c', 'f', '3057', '481', '5887', '847', 'c', 'x', 't', 'g', '5805', 'a', 'i', '2885', '403', 'x', 'c', '4815', '2765', 'c', '5181', 'l', 'e', '3843', '1171', 'u', '7867', 'z', 'e', '9349', '5011', 'h', 'x', '3193', 'i', '4595', '8621', '6007', '1879']

SOLUTION: a, c, e, f, g, h, i, k, l, t, u, x, z

PROBLEM: ['e', '779', '9705', 'v', 't', 'l', 'y', '9455', 'e', 'i', '6799']

SOLUTION:
e, i, l, t, v, y