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: ['c', 'a', 'p', 'p', '4203', '1587', '2953', '9809', '99', '5821', 't', 'i', '4213', '1809', 's', 'l', 'i', 'b', '9233', '3983', '7713', '1807', 'k', 'f', '7825', '5491', 'o', '1347', 'u', 'h', '3967', 'u', 'g', '6775', '1069', '9211', 'i', '3369', 'r']

SOLUTION: a, b, c, f, g, h, i, k, l, o, p, r, s, t, u

PROBLEM: ['4045', '4739', 'd', 'e', '6789', 'e', 'q', '4909', '9511', 'h', '9543', '6725', 'a', '3683', 'q', 'k', 'd', 'q', 'z', 'b', '3245', '9877', '9155', '7751', 'e', '1015', '2379', 'f', 'y', '1121', '9801', 'c', 'h', 'l', 'f', '67', 'v', 'v', 'y', 'c', '3871', 'v', '5893', 'a']

SOLUTION: a, b, c, d, e, f, h, k, l, q, v, y, z

PROBLEM: ['i', 'f', 'm', 'y', 'f', 'v', 'f', 'u', '6037', '3611', 'k', '7507', '6243', 'e', 'k', 'f', 'c', 'a', '9855', '8063', '6145', 'q', 'o', 'n', '8551', '5449', 'g', 'v', 'v', '2191', '2161', '769', 'z', 'z', 'h', '2495', '5467', '1629', 'l', '4523', '3621', '7097', 'f', '2453']

SOLUTION:
a, c, e, f, g, h, i, k, l, m, n, o, q, u, v, y, z