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: ['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: ['b', 't', '2199', 'e', 'i', '1883', '5137', '8495', 't', '7377', 'm', '7665', '2009', 'o', '3757', 'm', '861', 'm', 'l', '9229', 'c', 'r', 'q', 'i', 'm', '705', 'b', '4301', 'd', 'l', 'f', '5485', 'h', 'p', '4529', '7879', 'f', 'b', 'm']

SOLUTION: b, c, d, e, f, h, i, l, m, o, p, q, r, t

PROBLEM: ['6801', '2079', 'm', '6649', '8563', '1455', '9519', '4125']

SOLUTION:
m