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: ['1189', '7143', '993', '1513', '6449', '9749', '5963', '8159', 't', '3543', 'j', 'i', '4227', '1463', '6431', '4987', 'y', 'q', 'f', '321', 'm', 'r']

SOLUTION: f, i, j, m, q, r, t, 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: ['4787', 'c', '1727', '9863', '8147', '3931', 'b', '1133', '3023', '7427', '7837', 'n', '7921', 'o', 'c', '3973', '1949', 'x', 'g', 'b', 'd', '8559', '8661', '4465', 'z', '369', 'q', 'e', 'y', '8629', '7665', 'i', 'r', 'n', 'z', '9115', '1393', '4899']

SOLUTION:
b, c, d, e, g, i, n, o, q, r, x, y, z