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: ['s', '2507', '3091', 'g', '7643', '2573', 'w', 'r', '1977', 'q', 'c', 'j', '1335', '9671', '7317', '567', '2041', '5777', 'w', 'm']

SOLUTION: c, g, j, m, q, r, s, w

PROBLEM: ['3117', 'i', 'd', '7537', 'i', 'q', '4649', '7263', '3655', 'd', 'x', '8569', 'g', '2389', '3933', '7099', '563', '3055', '9941', 'm', 'c', '3529', '3577', 'x', 's', 's', '6153', '1731', '9679', 'f', '8839', '5183', '5', '6433']

SOLUTION: c, d, f, g, i, m, q, s, x

PROBLEM: ['e', 's', 'r', '5713', '7887', 'f', 'x', '5533', 'p', 'c', '6623', 'i', '6913', '1609', '6803']

SOLUTION:
c, e, f, i, p, r, s, x