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: ['r', 'j', '437', 'b', '5223', 'n', 'v', '437', 'd', '8285', 'k', 'j', 'r', 'p', 'n', 'e', 'n', 'j', 'o', '2651', 'j', '6365', 'q', 'q', '2159', 'g', '3641', '7727', 'c', '1197', 's', 't', 'n']

SOLUTION: b, c, d, e, g, j, k, n, o, p, q, r, s, t, v

PROBLEM: ['p', 'k', 'i', '753', 'u', 'm', '3817', '1597', 'l', 'm', 'a', 'i', 'b', 's', 'c', '2561', 'x', '5363', '1173', '8657', '2033', 'b', 'p', '3093', 'k', '6535', '307', '9925', 'b', 'q', 'q']

SOLUTION: a, b, c, i, k, l, m, p, q, s, u, x

PROBLEM: ['g', '8179', 'p', '7105', 'n', 'd', 'a', '4289', '4795', '9331', 'u', '5277', 'z', '4927', '8957', '7831', 'a', '7257', '7461', '2629']

SOLUTION:
a, d, g, n, p, u, z