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', 'w', '8949', '4025']

SOLUTION: s, w

PROBLEM: ['9013', 'e', 'm', 'p', 'k', '161', 'k']

SOLUTION: e, k, m, p

PROBLEM: ['m', 'x', 'q', 't', 'n', 'n', '4751', 'h', 'x', 'm', 'o', 'h', '8419']

SOLUTION:
h, m, n, o, q, t, x