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: ['6495', '2259', '8213', 'm', 'y', '3377', 'q', 'i', '1299', 's', 'w', '4331', 'h', '5459', '4059', '6637', '8069', '5367', '6025', 'l', 'v', '4503', 'd', 'x', 'w', '5067', '9019', 'd', '7919', '7299', 'v', '8957', 'v', '5341', '2617', '8169', 'n', 'y']

SOLUTION: d, h, i, l, m, n, q, s, v, w, x, y

PROBLEM: ['2541', '6763', '7717', '7939', '6097', '871', 'x', 'm', 's', '3649', '6223']

SOLUTION:
m, s, x