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:
['8357', 'x', 'w', '287', 'z', '2733', '1757', 'w', 'g', '1393', '7201', '4931', 'k', '5185', 'x', '6313', '2255', 'z', 'v', '3593', '6191', '4423', 'm', 'k', '3209', '3559', 'c', 'n', 'm', '5461', '2997', '235', '4045', '6597', 'v', 'e', 'p', 'c', 'k', 'd', '5529', '6241', 'u', 'f', '8067']
answer:
c, d, e, f, g, k, m, n, p, u, v, w, x, z


question:
['3043', 'r', 'm', 'i', '2653', 'i', '1703', '1125', '6299', '4863', 'n', 'h']
answer:
h, i, m, n, r


question:
['8769', '1951']
answer:

-1