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:
['g', 'x', 'l', 'e', 'd', '1345', '1763', 'm', 'c', '2057', 's', 'a', '4127', 'y', 'h', '8581', 'o', '9203', '4761', 'd', 'u', 'n']
answer:
a, c, d, e, g, h, l, m, n, o, s, u, x, y


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


question:
['v', 'o', 'o', '3295', 'o', 'k', '3121', '817', 'e', '8783', '7827', 's', '5121', 'a', 'f', '5215', 'g', '1713', 'c', 'u', 'u', '9415', 'n', 'u', '5921', '2743', 'h', 'o', '223', '9753', '2839', '6625', '2219', 'd', 'p', 't', 'd', '6849', 'z', 'u', 'm', 'j', '53', 'd', 'c']
answer:

a, c, d, e, f, g, h, j, k, m, n, o, p, s, t, u, v, z