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: ['5553', 'f', '3881', '8867', 's', 'd', 'a', '375', '7889', '3949', '2905', 'w', 'q', 'q', 'd', '4203', 'i', '2601', 'y', 'p', 'k']

SOLUTION: a, d, f, i, k, p, q, s, w, y

PROBLEM: ['j', 's', 'z', 'v', '5401', 'u', '8859', 'i', 'l', 'a', 'p', 'v', 'v', 'o', '3969', '4091', 'y', '6827', '1799', '5163', 'd', 'w', '4795', '5167', 'x', 'q', '2903', '1171', '5279', '449', '7901', 'u']

SOLUTION: a, d, i, j, l, o, p, q, s, u, v, w, x, y, z

PROBLEM: ['i', '2949', 'g', 's', '8887', '8811', 'f', 'y', 'k', '7707', 'b', 'w', 'f', 'h', 'm', 'd', '5135', 'k', 'z', 'n', '2745', '2775', 'm', 'g', '8493', '9349', 'u', '2663', '8657', '3451', 'y', 'n', '933', '1343', '7681', '8863', 'l', 'c', '9763', 'f', 'c', 'z', '9969', 'b']

SOLUTION:
b, c, d, f, g, h, i, k, l, m, n, s, u, w, y, z