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:
['2915', '6033', '5541', '4685', '1263', '6701', 's', '7269', 'g', '8033', '8171', '6917', 'l', '2913', '447', 'g', 'a', 'z', 'o', '7563', '5385', '5259', '5067', '4869', '2653', '6925', '7001', '8553', 'x', '1243', '9131', '5037']
answer:
a, g, l, o, s, x, z


question:
['8495', 'p', 'j', 'm', 'n', '9115', '1183', 'r', 'r', '8735', 'a', 'i', 'k', 'p', '8927', 'r', '9283', '9563', 'g', '2503', 'h', '1091', '5257', 'a', '3061', '2835', 'l', 'w', 'j', '7617', '8793', '7463', 'h', '8467', '7337', 'b', '4655', 'd']
answer:
a, b, d, g, h, i, j, k, l, m, n, p, r, w


question:
['m', '311', '7861', '1715', '6255', '9231', '6381', 'l', '9137', 'o', '3909', '1311', '3083', '7907', 'j', 'k', 'x', '6679', 's', '5461', '7637', '1027', '8579', '3951', '8655', '4335', '5041', '2465', 'g', 'g', '1373', 'f', '7447', '7453', 'u', '6897', 'v']
answer:

f, g, j, k, l, m, o, s, u, v, x