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: ['7823', '2933', 'k', '4139', '5585', 'f', 'c', 'm', '2035', 'q', 'z', 'l', '1999', 'q', 'p', '7291', '2091', 'v', '423', 'e', 's', '6089', '4763', '6739']

SOLUTION: c, e, f, k, l, m, p, q, s, v, z

PROBLEM: ['r', 'n', '7583', '8697', '7927', 'l', '5003', '1363', 'p', 'e', 'q', '6227', '6915', '8619', '9011', 'n', '3063', '3799']

SOLUTION: e, l, n, p, q, r

PROBLEM: ['3037', '8797', 'n', 'b', 'e', 'r', '5297', '3329', 'i', '2561', '7651', 'p', 'f', '2865', 'm', 'y', '2041', '1059', 'h', 'y', '3485', 'h', '9409', '1779', '8561', 'n', 'd', 'b', '8251', 'y', '2867', 'y', 'y', '193', '2251', 'g', '6639', '9781', '9913', 'r', 'e', '6117', 'h', '351']

SOLUTION:
b, d, e, f, g, h, i, m, n, p, r, y