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: ['231', 'r', '5673', 'j', '589', 'z', '4659', 'a', '3763']

SOLUTION: a, j, r, z

PROBLEM: ['p', '3981', 'e', '5949', 'p', '4075', '1919', 'w', 'r', '8059', '4303', 'f', '5201', '2255', '2737', '7395', '8809', 'j', 'z', 'n', '4797']

SOLUTION: e, f, j, n, p, r, w, z

PROBLEM: ['6157', '563', '1217', '5241', '4989', 'f', '6443', 'b', 'g', '9347', '6407', '2743', '977', '9097', 'h', 'u', '9163', 'e', 'v', '881', '2187', 'b', '9161', 'u', 'e', '3813', 'b', '5411', 's', 'o', 'i', 'c', '5483', '8071', 'v', '2981', 'n', 'x', 'a', 'j', '5709', 'n', '5335']

SOLUTION:
a, b, c, e, f, g, h, i, j, n, o, s, u, v, x