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: ['8879', 'x', '1383', '4925', '2867', 'j', 't', 'e', 'w', 'p', 't', 'w', 'l', '7447', '1877', '7747', 'k', 'b', 'x', '8565', 'q', '8575', '5711', '2949', '5637', '2197', '4905']

SOLUTION: b, e, j, k, l, p, q, t, w, x

PROBLEM: ['4397', '2685', '9539', '4343', '6697', '7693', 'g', 'c', '3587', '4691', 'j', '8931', '7397', '2103', '3431', 'u', 'l', 's', 'v', 'q', 'd', '1289', 'h', '1695', 'h', 'j', 'e', '1225', 'e', '7893', 'o', 'i', '3351']

SOLUTION: c, d, e, g, h, i, j, l, o, q, s, u, v

PROBLEM: ['f', 'o', 'j', 'l', 't', 'q', 'r', '4149', '6607', '9903', '6469', 'f', 'b', '3467', 'a', 'p', '2001', '6291', '2275', '4189', 'o', '5331', 't', '1373', '389', '7235', '5569', '6969', 'b', 'p', '1551', 'v']

SOLUTION:
a, b, f, j, l, o, p, q, r, t, v