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:
['t', 'h', '6141', 'g', 'f', 'z', 'n', 'b', 'k', '9059', 'y', 'p', '4289', '2683', 'a', '3267', 'w', 'p', 't', '3623', '7759', 'a', 'o', 'm', '9815', 'q', 'u', '8051', '6871']
answer:
a, b, f, g, h, k, m, n, o, p, q, t, u, w, y, z


question:
['6249', '1235']
answer:
-1


question:
['155', 'j', 'g', 'f', 'p', 'p', '6559', '6059', '6711', '6611', '591', '1999', '5241', '3989', 'f', 'r', '1307', '115', '2403', '3405', 't', 'h', 's', '3659', 'n', 'p', '2773', 's', '1641', '1739', 'i', 'o', 'k', 'u']
answer:

f, g, h, i, j, k, n, o, p, r, s, t, u