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:
['7823', '2933', 'k', '4139', '5585', 'f', 'c', 'm', '2035', 'q', 'z', 'l', '1999', 'q', 'p', '7291', '2091', 'v', '423', 'e', 's', '6089', '4763', '6739']
answer:
c, e, f, k, l, m, p, q, s, v, z


question:
['3127', '9253', '5667', '9453']
answer:
-1


question:
['n', '8079']
answer:

n