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:
['c', '7039', 'g', '1899', 'r', '507', 'c', '2587', '3865', '1729', '3927', 'r', '3535', '2791', 'm', 'l', 'r']
answer:
c, g, l, m, r


question:
['o', 'h', 'z', 'n', 'e', 'y', 't', '4371', 'm', '1059', '4853', '8529', 'l']
answer:
e, h, l, m, n, o, t, y, z


question:
['6035', '3623', '5479', 't', '4507', '6265', 'q', 'n', '3627', '5177', '3101', 'u', '6893', '6119', '8399', '9345', '4399', '5341', '1783', '4837', 'i', 'v', '2077', 'p', '6345', 'i', '2967', 'w', '4889', '2403', '8289', 'n', 'o', '293', '6815', 'f', 'y', '4461']
answer:

f, i, n, o, p, q, t, u, v, w, y