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: ['2775', '7507', 'c', '4417', '3449', 'y', 'z', 'e', 'f', '9515', '8555', '7269', '8353', '4239', '4347', '4479', '8645', '9925', 'o', 'h', 'o', '8641', 'y', '3251', '1191', 't', 'x', 'z', '7203', 'b', 'b', '7545', '7283', 'z', 'y', '8127', 'x', 'l', '6251', 'y']

SOLUTION: b, c, e, f, h, l, o, t, x, y, z

PROBLEM: ['p', 'p', '7899', 'u', '971', '7289', 't', '5217', 'k', 'z', 'y', 'y', '6905', '9499', '4085', 'x', '955', 'v', 'j', '9049', '7927', '1757', '193', '2181']

SOLUTION: j, k, p, t, u, v, x, y, z

PROBLEM: ['8003', 's', 'r', 'x', 'r', '951', '6283', 'n', '8101', 'o', 'o']

SOLUTION:
n, o, r, s, x