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: ['u', '635', '5249', '9457', 's', '9317', '9407', 'l', 'w', '9705', 'k', '429', '5489', 'e', 'd', '2457', 'o', '4665', '1675', 'l', 'y', 's', 'o', 't', '4285']

SOLUTION: d, e, k, l, o, s, t, u, w, y

PROBLEM: ['h', 'g', '4563', 'v', 'm', '107']

SOLUTION: g, h, m, v

PROBLEM: ['x', 'z', 'h', '9', 'j', '839', '4255']

SOLUTION:
h, j, x, z