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: ['m', '7517', '9361', '9567', '8785', 'k', '5699', '3585', 'v', '1913', '1651', 'g', 'p', '2731', 'q', 'h', '467', 'r', '1091', '9801', 'a', '6645']

Answer: a, g, h, k, m, p, q, r, v


Question: ['y', 'i', '257', '3695', 's', '6717', '4817', '4117']

Answer: i, s, y


Question: ['u', '5681', 'f', 'a', '387', 'l', 'f', '6297', '1441', '6315', '5513', '4975', 'i', '9335', 'k', '3967', '8709', 'i', 'y', 'f', 'a', '6653', 'j', 'f', '315', '4091', '3659', 'p', 'c', '2657', '9773', '7239', 'm', '3151']

Answer:
a, c, f, i, j, k, l, m, p, u, y