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:
['6627', '8037', 'q', 'e', 'j', 'p', '9613', '9317', 'm', 'm', '5345', 'f', '8105', '5665', '4175', '4793', '3707', 'i', 'b', '6745', '747', '8329', '1481', 'b', '8949', 'n', '4803', '1359', '3533', 'f', '543', '3003', '6943']
answer:
b, e, f, i, j, m, n, p, q


question:
['9385', '4021', 'y', '9629', 'u', '7623', 'd', '5155', 'x', '2605', '8893', 'l', 'p', 'a', 'm', '6699', 'i', '4503', '6623', 'm', 'l', '6115', 'p', 'w', '9691', '811', '4769', '2659', 'x', 'c', '6513', '5499', 's', 'q', 'f', 'v', 'z', 'w', 'z', '1361']
answer:
a, c, d, f, i, l, m, p, q, s, u, v, w, x, y, z


question:
['x', 'q', 'j', 'w', '9569', 'g', 'j', '3997', 'g', 'i', '3037', 'f', 'u', 't', '2079', 'x', 'y', '9357', 'z', 'y', '2057', 'e', '4499', 't', '3191', 'b', 'd', 'y', 'v', 'n', '2965', 'a', '1769', '6547']
answer:

a, b, d, e, f, g, i, j, n, q, t, u, v, w, x, y, z