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:
['u', 'o', 'b', 'b', '5873', 'w', 'v', '4171', '7957', '3501', '2563', 'l', 'q']
answer:
b, l, o, q, u, v, w


question:
['n', 'g', 'u', '2873', 'k', '4411', 'w', '8179', 'w', 'w', 'f', 'g', 'e', '7837', '3055', 'z', 's', '6037', 'n', '1479', 'c', '5311', 'i', 'w', 'z', '1891', '9663', 'y', 'f', 'h']
answer:
c, e, f, g, h, i, k, n, s, u, w, y, z


question:
['5973', 'o', '5657', '2731', 's', '9045', '8509', '575', '3179', '8047', 'm', 'j', '3421', 'l', 'k', '8825', 'l', '915', '7285', '6063', '1705', 'v', 'm', 'j', 'b', 'd', 'q', 'f', 'w', 'q', 'v', '9255', 'o', 'y', '2529', 'v', '9625', 'n', '6319', '2773', 'p', '675', 'n']
answer:

b, d, f, j, k, l, m, n, o, p, q, s, v, w, y