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.
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Question: ['u', '4731', 'l', 'p', '1997', '601', 'n', 'l', 'p', '211', '7355', '6537', 'w', 'x', '1741', '8145', '3689', 'm', 'y', '6945']

Answer: l, m, n, p, u, w, x, y


Question: ['9013', 'e', 'm', 'p', 'k', '161', 'k']

Answer: e, k, m, p


Question: ['8193', '3199', '1793', 'd', 'n', '1553', 'w', '4165', 'v', '4069', '8223', 'j', 'd', '5799', '6195', '8971', '3233', '5073', 'h', 'g', 'a', 'i', '8577', 't', '7541', 'u', '8805', '9793', 'b', '1495', 'y', '8133', '7355', '3755', 's', '4209', '3047', 't', 'e', 'm', '7081', '1419', 'k']

Answer:
a, b, d, e, g, h, i, j, k, m, n, s, t, u, v, w, y