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: ['9627', '9879', '5421', '4755', '1533', '6727', 't', '7641', 'd', '3929', 'h', '3989', '8441', 'k', 'p', '2653', 'm', 'b', 'i', '3431', '4907', '5687', 'g', 'h', '9185', '5051', 'k', '7135', '709']

SOLUTION: b, d, g, h, i, k, m, p, t

PROBLEM: ['2799', '7519', '345', 'e', 'l', '9369', '4703', '4111']

SOLUTION: e, l

PROBLEM: ['v', 'y', '7967', '6803', 'x', 'v', 's', 'e', '9649', '6931', '7897', 'n', '8639', 'q', '7525', '4465', 'd', '6985', 'o', '4921', '9427', 'h', '7351', 'u', '5609', 'l', 'b', '3695', '4151']

SOLUTION:
b, d, e, h, l, n, o, q, s, u, v, x, y