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: ['f', '7573', '2067', 'n', '3671', '7969', '7889', '4893', '6501', 'l', 'y', '4331', 'a', 'e', '2081', '3863', 't', 'j', '7921', 's', '7203', '7797', 'f', '4279', '1299', '987', '5003', '9071', '9559', '6061', '1889', '2653', 'm', 'w', '665', '7343', '9763', 'r', '6343', '9393', '9289']

SOLUTION: a, e, f, j, l, m, n, r, s, t, w, 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: ['1729', 's', '9079', 'u', 'q', '547', 'n', 't', '1543', '4109', '8977', 'e', 'f', 'l', '4963', 'j', 'y', 'l', 'f', '2419', 'v', '8009', 'm', '685']

SOLUTION:
e, f, j, l, m, n, q, s, t, u, v, y