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', 'i', '7725', '2483', 'e', 'j', '5337', 'b', '6835', '8231', 'm', 'v', 'a', '1475', 'n', '5823', 's', 'm', '7313', '2841', '2585', '4673', 'u', '2083', 'z', 'd', 'p', '2117', 'i', '587', 'i', 'a', '2527', '7967', '6567', 'n', '6145', 'r', 'f']

SOLUTION: a, b, d, e, f, i, j, m, n, p, r, s, u, v, z

PROBLEM: ['g', 'u', 'q', '1375', '9491', 't', 'w', 'c', 'v', 'y', '3169', '1607']

SOLUTION: c, g, q, t, u, v, w, y

PROBLEM: ['h', 'm', '4583', '8663', '4323', 'a', '1959', 'l', 's', '5673', '15', '7471', '523', 'e', '3347', 'x', 's', '3285', 'v', 'z', 'n', 'i', '499', '833', 'l', 'u', '5539', 'r', 'd', '5661', 'y', '8223', '3299', 'n', '2943', 'r', '5715', '6641']

SOLUTION:
a, d, e, h, i, l, m, n, r, s, u, v, x, y, z