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:
['8051', 'h', 'g', 's', 't', 'p', 'w', 'x', 's', '8521', 'm', '9719', 'j', 'n', 'i']
answer:
g, h, i, j, m, n, p, s, t, w, x


question:
['n', '7337', '6887', '2203', '4663', '2837', '6451', '959', '8027', 'p', 'v', 'q', 'g', '8059', '6151', 'v', '7097', '6583', '7637', '2367', 'w', '9603', '5365', '3773', '1707', 'k', 'x', 's', 'c', 'u', '3641', '6137', '1207', 'k', '5531', '4543']
answer:
c, g, k, n, p, q, s, u, v, w, x


question:
['5215', '4609', '7853', '5365', 'w', 'n', '7459', 'z', 'r', '5075', 'd', 'w', 'w', 'y', '83', '4557', 'r', '1125', 'a', '8217', 'v', 'i', '2739', '5993', '5897', '1045', 'x', 'y', 'k', '5457', 'd', '1469', 'l', '9021', 's', 'k', 'z', 'w']
answer:

a, d, i, k, l, n, r, s, v, w, x, y, z