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: ['i', '9215', 'n', 'p', '4815', '8757', 'm', '1755', 'c', 'z']

SOLUTION: c, i, m, n, p, z

PROBLEM: ['8739', 'v', 'm', '6277', 'l', 's', '109', '8057', '3835', 'd', 'u', 'f', 'w', 'd', 'p', '7705', '3643', '4455', 'u', 'p', 'u', '9407', 'g', 'w', '595', 'z', '6827', '6879', 'w', 'w', '6973', 'm', 'e', '1553', 'v', '3529', '8953', '3903', '5713', '8249', 'e', '1113', 'b', 't', 'r']

SOLUTION: b, d, e, f, g, l, m, p, r, s, t, u, v, w, z

PROBLEM: ['h', '3753', '2617', 'u', 'n', 'a', '3661', '2597', '8027', '1751', 'q', '4197', 'e', 'o', '7073', 'm', 'j', '4317', '3103', '5289', 'q', '8855', 'g', 'q', 'a', 'e', '6479', '6107', '2503', '8183', 'h', '8097', 'w', 'x', 'v']

SOLUTION:
a, e, g, h, j, m, n, o, q, u, v, w, x