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

SOLUTION: g, h, m, v

PROBLEM: ['6697', 'j', '1571', '4989', 'o', '1143', 'i', '2969', '2541', '4899', 'i', '4751', 'n', 'b', '801', '4357', '3855', '49', 'm', '211', '7281', '121', '5231', '8313', '8967', '8043', '7699', 'r', '4315', '8637', '3339', '4437']

SOLUTION: b, i, j, m, n, o, r

PROBLEM: ['6681', '4229', '4123', 'y', '3061', '6807', 'h', '7791', 'm', '8865', 'v', '4901', '3145', 'e', '4827', 'u', '2223', '2613', '3319', 'v']

SOLUTION:
e, h, m, u, v, y