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: ['895', '2049', '8839', '1773', 'v', '467']

SOLUTION: v

PROBLEM: ['5761', '2289', '577', 't', '125', 'i', 'g', '9693', '747', 'd', '4829', '9587', 'f', 'k', 'w', 'v', '8607']

SOLUTION: d, f, g, i, k, t, v, w

PROBLEM: ['j', '8955', 'p', 'e', 't', '1913', '771', '3591', 'l', '5643', 'b', '1353', 'm', '2343', '9703', 'h', 'g', 'h', 'u', '7815', '703', 'g', 'q', '351']

SOLUTION:
b, e, g, h, j, l, m, p, q, t, u