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: ['h', 'g', 'j', 'i', 'y', '7799', 'y', 'e', 'y', 'e', '6757', '3349', '1213', '191', 'd', '2149', '849', '8325', 'b', '6087', 'w', '7211', '7801']

SOLUTION: b, d, e, g, h, i, j, w, y

PROBLEM: ['1063', 'f', 'm', 'i', 'x', 'i', 'd']

SOLUTION: d, f, i, m, x

PROBLEM: ['n', '3277', 'v', 'v', 'a', '9157', '6019', 'a', '335', '9563', 'a', 'f', '757', '8831', 'u', '7435', 'b', 'x', 'o', '4909', '2671', '8435', '5219', '2331', 'y', '1157', '1819', 'r', 'g', '5051', 'x', 'i', '1535', '3289', 'z']

SOLUTION:
a, b, f, g, i, n, o, r, u, v, x, y, z