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: ['x', 'i', 'r', '6011', 't', 'f', 'b', 'i', '8367', '4051', '1459', 'f', '5583', '9609', 'l', 'q', 'g', '8443', 'o', '8697', '7053', '8325', 'k', '7021', 'q', 'm', '6899', '9981', '8985', 'i', 'j', '8043', 'k', '535', '7603', '7629', 'k', '2779', 'g', '2049', 'x', 'd', '8527', 'k', 'q']

SOLUTION: b, d, f, g, i, j, k, l, m, o, q, r, t, x

PROBLEM: ['v', '6635', '5395', '3263', '4391', 'h', '1521', 'f', '9861', '6125', '1673', '3679', '8681', '4967', 'f', 'a', 'c', 'k', 'n', '4155', 'e', 'm', 'i', '1699', 'r', 'f', 'u', 'r', '3451', 'v', '7239', 'o', '4359', 'l', 'a', '2925']

SOLUTION: a, c, e, f, h, i, k, l, m, n, o, r, u, v

PROBLEM: ['u', 'x', '5833', 'i', '4961', '6415', 'x', 'a', 's', '8233', 'd', '7367', '1071', '9515', 'i', '2307', '9559', 'l', '4387', '7745', '3393', 'u', 'n', '795', 'q', 'o', '6705', 'u', '2259', 'e', '7297']

SOLUTION:
a, d, e, i, l, n, o, q, s, u, x