instruction:
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:
['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:
['p', 'v', '1099', 'y', '1313', 's', '181', 'u', 'e', 'u', '8435', '4125', '8661', 'c', '4605', 'f', 'x']
answer:
c, e, f, p, s, u, v, x, y


question:
['p', '9741', '1961', '1427', 'r', 'l', '2133', '5795', '3891', '1223', '1441', 'i', 's', 'p', '5015', 'k', 'w', '409', 'g', 'g', 'j', '9111', 'd', '4511', '4059', '1627', 'c', '611', '2529', 'a', 'w', 'u', 'w']
answer:

a, c, d, g, i, j, k, l, p, r, s, u, w