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:
['e', 'k', '7569', '6387', '4593', '2445', '345', '2905', 'h', '3119', '7001', 'x', 'a', '2943', '3635', 'l', 'q', 'z', 'g', '2657', '7849', 'i', '9413', 'm', 'e', '2951', 'd', '2963', 'b', 'u', 't', 'i', '1141', 'c', 'm', '8607', 's']
answer:
a, b, c, d, e, g, h, i, k, l, m, q, s, t, u, x, z


question:
['6143', 'y', '5505', '9813', 'r', 'v', 'u', '8681', '2387', 'u', 'o', 'm', '9793', 'm']
answer:
m, o, r, u, v, y


question:
['o', 'i', '4473', '8217', '6763', '4237', 'o', '3195', '9227', '7725', '7225', 'u', '8275', '9883', 'j', 'f', '9331', 'e', '6989', '8879', '5907', 'g', '4903', 't', '5923', '7147']
answer:

e, f, g, i, j, o, t, u