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: ['m', '6443', 'd', 'o', 'p', 'q', '3765', 'k', 'm', 'y', 'j', '3531', 'y', 't', '671', 'j', '3699', 'a', 'i', '1843', 't', 'd', '1205', 'k', 'h', '1209', '2913', '1301', 'k', 'd', '1769', '7985', 's', 'p', 'f', '4583']

SOLUTION: a, d, f, h, i, j, k, m, o, p, q, s, t, y

PROBLEM: ['9307', 'i', 'c', 'y', '6219', '251', '7345', '3023', 'j', '5719', 'c', 'q', 'i', 'o', '4027']

SOLUTION:
c, i, j, o, q, y