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: ['q', 'g', 's', 'g', 'z', '987', '777']

SOLUTION: g, q, s, z

PROBLEM: ['4041', 'l', 'g', '9571', '9295', '1395', 'l', 'p', 'f', 'w', 'g', '1721', '2421', 'w', 'z', '2235', 'p', '7851']

SOLUTION: f, g, l, p, w, z

PROBLEM: ['9645', 'q', 'q', '6983', 'n', '7433', 'f', '7203', 'g', 'p', 'k', '5809', 'j', '1113', '3849', 'w', 'x', 'h', 'b', '7731', 'h', 'j', '6481', 'e', '951', '7059', 'r', 's', '9099', '8529', 'f', '2733', '6989']

SOLUTION:
b, e, f, g, h, j, k, n, p, q, r, s, w, x