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:
['3561', 'd', '9697', 'd', '7761', 'a', '2833', 'c', '2921', 't', '691', 'g', '4797', 'b', '3913', 'f', 'q', '7807', 'j', '3577', 'j', '1775', '2897', '2589', '993', '8595']
answer:
a, b, c, d, f, g, j, q, t


question:
['4045', '4739', 'd', 'e', '6789', 'e', 'q', '4909', '9511', 'h', '9543', '6725', 'a', '3683', 'q', 'k', 'd', 'q', 'z', 'b', '3245', '9877', '9155', '7751', 'e', '1015', '2379', 'f', 'y', '1121', '9801', 'c', 'h', 'l', 'f', '67', 'v', 'v', 'y', 'c', '3871', 'v', '5893', 'a']
answer:
a, b, c, d, e, f, h, k, l, q, v, y, z


question:
['6909', '913', 'h', '1811', '5601', 'g', '1943', '4465', '8377', 'h', 'y', '6827', '8677', '397', 'h', 'b', 'j', '8979', 'p', '4533', 'l', '7469', '8419', '5849', 'm', 'c', 'k', '1023', '6521', '43', '4413', 'v', 'y', 'k', 'a', 'm', 'y', '8951', 's', '9429', '9369', '1013']
answer:

a, b, c, g, h, j, k, l, m, p, s, v, y