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.

[EX Q]: ['1595', '2915', 'o', 't', 'c', 'h', '3969', '5407']
[EX A]: c, h, o, t

[EX Q]: ['2293', 'p', '9787', '7241', '8689', 'u', '3141', 'h', 'c', 'b', 'f', 's', '319', 'c', 'p', '6909', 'p', 'f', '1717', 'd', '2285', 's']
[EX A]: b, c, d, f, h, p, s, u

[EX Q]: ['f', 'b', 'a', '5073', '1451', '11', 'h', '7627', 'i', 'd', 'u', '3435', '8367', 'm', '1259', '2397', '4799', 'w', '3849', '2587', '8979']
[EX A]:
a, b, d, f, h, i, m, u, w