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', 'h', 'g', 'g', 's', 'h', '2849', '2705', '1185', 'x', '5789', '8221', 'e', 'x', 'g', 'b', '4903', 'q', '1563', 'r', 'k', 't', '9047', 'p', 'p', '9397', 'u', '7473', 'f', 'o', 'y', '1957', '1039', '9905', 'i', '4829', 'q', 'w', 'k', 'p', 't', '563', 'g', 'l']

SOLUTION: b, e, f, g, h, i, k, l, o, p, q, r, s, t, u, w, x, y

PROBLEM: ['m', '957', 'a', '6585', '6659', 'n', '581', 'z', '5891', '2885', 'j', '1395', 'd', 'b', '8249', '41', 'x', 'v', 'c', 'b', 'o', '7775', '9837', '5219', 'h', '671', '9461', '1367', '2199', 'g', 'a']

SOLUTION:
a, b, c, d, g, h, j, m, n, o, v, x, z