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.

['n', '9571', '2983', '7597', 'v', 'y', '1993', '1403', '8309', '7043', 'c', '7329', 'p', '4479', 'p']
c, n, p, v, y

['5737', 'b', 'e', 't', '7419', 'n', 'y', '5225', '6485', 'b', '1343']
b, e, n, t, y

['7039', '2093', '7603', 'l']

l

