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.
--------
Question: ['1449', 'a', '6261', '303', '4651', 'n', 'u', '1595']

Answer: a, n, u


Question: ['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']

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


Question: ['m', '79', 'o', 'z', 'm', 'p', '2627', '5761', '589', 'f', '2281', '1741', '4553', '2851', 'y', '9667', '6947', '7691', 'r', '3973', 'w', '9623', 'w', '1283', 'b', 'w', 'j', '6175', 'a', '8965', '1833', '8011', '4175', '4941', '631', 'd', '3185', 'y']

Answer:
a, b, d, f, j, m, o, p, r, w, y, z