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:
['3561', 'd', '9697', 'd', '7761', 'a', '2833', 'c', '2921', 't', '691', 'g', '4797', 'b', '3913', 'f', 'q', '7807', 'j', '3577', 'j', '1775', '2897', '2589', '993', '8595']
answer:
a, b, c, d, f, g, j, q, t


question:
['9223', 'w', '8631', '4453', '9975', 'y', '9747', 'g', '7077', '2593', '6015', 'n', '7345', 'i', '7807', '299', 'q', '3629', '2545', 'k', 'm', 'q', '5155', '5633', 'x', 'q', 'i', '27', 'f', '7919', 'p', '4835']
answer:
f, g, i, k, m, n, p, q, w, x, y


question:
['g', '9473', '1473', '4883', '9961', 't', '213', '7189', '4487', '685', '4155', 'c', '7315', '8969', '5841', 'l', 'm', 'f', '9877', 'j', 't', 'n', 'f', 'm', '5401', 'n', 'a', 'm', '2997', '8333', 'u', 'b', 'i', '4545', '6653', 'h', 'p', 't', '547']
answer:

a, b, c, f, g, h, i, j, l, m, n, p, t, u