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: ['2293', 'p', '9787', '7241', '8689', 'u', '3141', 'h', 'c', 'b', 'f', 's', '319', 'c', 'p', '6909', 'p', 'f', '1717', 'd', '2285', 's']

SOLUTION: b, c, d, f, h, p, s, u

PROBLEM: ['4641', '2881', 'c', '4827']

SOLUTION: c

PROBLEM: ['695', 'x', '3875', 'q', '2513', 't', '6315', 't', '7253', 'g', '2825', '9753', 'n', 's', 'k', '3907', '807', '9123', 'v', 'p', 'k', 'q', 'n']

SOLUTION:
g, k, n, p, q, s, t, v, x