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: ['887', 'p', '3819', '2727', '1407', 'b', 'n', '737', 'd', 'w', 'q', '6877']

SOLUTION: b, d, n, p, q, w

PROBLEM: ['5463', '5683', 'w', '4071', '3997', 'i', '9677', 'q', 'l', 'v', 'w', '5325', '197', 'g', 'g', '3227', '3477']

SOLUTION: g, i, l, q, v, w

PROBLEM: ['6097', 's', 'w', 'n', '3011', 'c', 'x', '1811', 'q', '6559', 'h', 'x', '7191', '1395', 'z', 'd', '5381', 'h', 'v']

SOLUTION:
c, d, h, n, q, s, v, w, x, z