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:
['h', '6865', '4019', '8571', 'y', '5575', '7835', '9537', 'n', '875', 't', 'a', 's', '2769', 'p', '1607', 'n', '4087', '961', '7869', '5085', '2131', '4867', 'j', 'h', 'y', '3105', '6609', 's', 'l', '3399', '5013']
answer:
a, h, j, l, n, p, s, t, y


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:
['7609', '9131', 'p', '3947', 'h', '9699', '8021', '8923', '1415', '9083', 'z', '3917', '3507', 'h', '1415', '2839', '7873', '4961', 'v', '9793', '1279', '6433', 'j', 's', 'e', '9231', '6209', '5283', 'c', 'b', '2457']
answer:

b, c, e, h, j, p, s, v, z