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: ['7109', '1243', 'f', 'z', 'h', 'd', '6169', 'v', 'h', '3609', '3181', 'd', '3661', '7193', '7341', '9127', 'r', '1623', '5813', 's', 'd', '4011', '4983', 'n', '4195']

SOLUTION: d, f, h, n, r, s, v, z

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: ['6247', '7717', 'g', 's', 'x', 'n', 'l', 'd', 's', '2771', '597', '7243', 'x', '5971', 'u', '4039']

SOLUTION:
d, g, l, n, s, u, x