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: ['a', '3281', '9123', '5443', 'w', 'w', 'p', '9275', 'v', 'm', '3549', 'l', 'y', 'l']

SOLUTION: a, l, m, p, v, w, y

PROBLEM: ['z', 'l', 's', 'f', 'j', 'x', '1125', 'd', '37', '5009', '9187', 'b', '8683', '8841', 'y', '9955', '1571', 'm', '347', '3679', '5797', '2133', 'g', 'u', '9817', '6347', '2067', '1927', '167', '4215', '45', 't', 'd', '6599', '4751', 'g', 'l', 'u', '7881', 's']

SOLUTION: b, d, f, g, j, l, m, s, t, u, x, y, z

PROBLEM: ['9877', 'm', 'r', '4177', '7697', 't', '8915', '4127', '6867', 'n', 'x', 'k', 'b', '5675', 'n', 'l', 'e', 'd', '6825', '3797', 'n', '4211', '1221', 't', '9633', 'b', '8163', 'g']

SOLUTION:
b, d, e, g, k, l, m, n, r, t, x