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: ['57', 'j', 'n', '877', 'u', 'w', 'j', 'f', '8977', 'h', '469', '9417']

SOLUTION: f, h, j, n, u, w

PROBLEM: ['o', 'z', 'h', '3965', 'n', '3009', '173', '997', '3987', '5799', '2331', 'p', 'x', '897', '8213', '451', 'u', 't', 't', '9917', '4501', 't', 'c', 'i', 'w', 'w', 'u', '2977', 't', 'b', '4161', '9281', 'w', 'f', '3137', '5745', 'e', '673', '6363', 'h', 'q', 'x', 'm', '9505']

SOLUTION: b, c, e, f, h, i, m, n, o, p, q, t, u, w, x, z

PROBLEM: ['5749', '9855', 'c', 'u', 'x', '467', '4409', 'o', '3501', 'd', '2201', '21', '695', '219', '9985', '2469', '5983', '9393', 'y', 'o', '8551', 'p']

SOLUTION:
c, d, o, p, u, x, y