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:
['a', 'w', 'm', 'g', 'c', '5475', '7391', 't', '1049', 'p', 'd', '1397', 'k', 'x', 'j', '2525', 'f', '741']
answer:
a, c, d, f, g, j, k, m, p, t, w, x


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:
['4019', 'f', '6293', '8065', 'l', 'g', 'h', 'n', 'g', 'q', 'e', '7429', 't', 'w', 'n', 'a', 'e', 'g', '5177', '3965', '8305', 'u', '7719', '9149', 'j', '8613', '851', 'j', 'i']
answer:

a, e, f, g, h, i, j, l, n, q, t, u, w


