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: ['c', '8389', 'j', '6113', '5843', 'f']

SOLUTION: c, f, j

PROBLEM: ['587', '3903', 'z', 'l', 'k', '5693', 'x', '1695', 'c', '3185', 'g', '9491', '8185', '1285', '2533', '6825', '3187', '6039', 'e', '251', 'w', '7741', '9573']

SOLUTION: c, e, g, k, l, w, x, z

PROBLEM: ['4123', '7703', 'j', 'u', '1549', '4107', '4861', 'd', 's', '3421', 'm', '8023', 'g', 'r', 'n', '9223', '8427', '9071', 'j', 'n', 'r', 'b', '1757']

SOLUTION:
b, d, g, j, m, n, r, s, u