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: ['747', '5385', '5313', 'p', '9581', 'r', '1339', '3919', 'e', 'e', '8057', '7739', 'i', 'e', '3311', '963', 'g', 'h', '7349', 'y', '1493', 'e', '3055']

SOLUTION: e, g, h, i, p, r, y

PROBLEM: ['e', 'n', 'y', 'f', 'l', 'h', '455', 'y', '591', 'm', '9041', 'b', 'b', 'o', '4215', '5009', 'o', 'a', '4369', 'u', '6911', '4825', 't', 'k', '6063', '2939']

SOLUTION: a, b, e, f, h, k, l, m, n, o, t, u, y

PROBLEM: ['b', '6071', 'n', '1299', '299', 'g', '3637', 'p', 'j', 'h', 'n', '2541', 'r', '815', 'q', 'l', 'w', 'y', '4929', '905', '5951', 'z', 'q', 'o', '6255', '9237', '7583', 't', 'b', 'x', '3533', 'q', 't', '8975', '4851', 'h', 'q', '2995', 'm', '9777']

SOLUTION:
b, g, h, j, l, m, n, o, p, q, r, t, w, x, y, z