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:
['d', '5285', 'z', 't', 'i', '719', 'z', 'b', '3603', '4781', 'o', 'g', 'j', 'd', 'r', 'a', 'x', '5829', '4907', '7395', '993', '2109', '1745', '415', '7525', '1029', '7791', '5321', 'h', '6391', 'g', '4613', '9191', 'o', '7365', '1811', '9695', 'w']
answer:
a, b, d, g, h, i, j, o, r, t, w, x, z


question:
['o', '1099', 'r', '8995', 'o', '2909']
answer:
o, r


question:
['7957', '8861', 'v', 'p', 'i', 'c', 'q', 'n', 's', '15', 'n', 'f', '537', 'v', 't', '3241', '9633', 'p', 'x', 'q', '1689', '6663', '2723', 'h', 'd', '1629', 'b', '8765', '613', 'w', '3455', 'd', 'u', 'c', '2769', 'r', '7701', '9059', 'g', '2427', 'k', '7793', '3159', '3383']
answer:

b, c, d, f, g, h, i, k, n, p, q, r, s, t, u, v, w, x