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:
['7301', '7999', 'x', 'r', '6881', 'e', '609', 's', '7495', 'a', 's', '1961', 'q', 'x', '373', '6289', '4847', '5969', 't', '5487', '7639', '9039', '2395', 'b', 'd', '1447', 's', '8137', 's', '443', 'f', 'z', '4823', 'k', 'i', 'o', '4739', 'w', 'f', '8853', 'a']
answer:
a, b, d, e, f, i, k, o, q, r, s, t, w, x, z


question:
['565', 'i', '615', '3047', 'm', '195', '7547', '3003', '9213', '9063', 'c', '5099', 'v', '5003', '9053']
answer:
c, i, m, v


question:
['7569', '4331', 't', 'g', 'u', '927', 'u', '3207', '355', 'x', 's', 'i', 'k', '175', 'd', 'o', 'o', 'f', 's', 'm', 'c', 'j', '9301', '363', '7355', 'k', 'r', 'a', '1455', '1179', '2113', '519', '2161', '6095', '3047', '7887', '2271']
answer:

a, c, d, f, g, i, j, k, m, o, r, s, t, u, x