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: ['r', 't', '3539', 'z', 't', '6055', 'r', '5787', '8469', 'p', 'h', '9729', 'z', '1637', '5873', 'c', '3597', '4411', 's', 'k', 'q', '6471', '5375', 'e', 'v', 'i', '7425', 'h', '9079', 'd', '1585', '6011', 'x', '5669', '5219', '4951', '4765', '8285', '2811', 'c', '1805', '6463']

Answer: c, d, e, h, i, k, p, q, r, s, t, v, x, z


Question: ['m', '6537', '4063', '6413', 'k', 'd', '2479', 'p', '2251', 'q', '7079', 'r', 'd', 'p', '3347', '1391', '9847', '4487', 'u', '6951', '5285', '5837', '6747', 'r', 's', 'c', 'x', 'b', 'q', 'y', 'd', '331', '679', 'v', '1919', 'f', 'p', '1267', '3151']

Answer: b, c, d, f, k, m, p, q, r, s, u, v, x, y


Question: ['6367', '1019', '2441', '4023', 'm', 's', '2443', 'f', 'z', '6133', '8425', 'h', '5243', 'h', 'l', '8373', 'i', '2355', '5971', 'h', '4585', 'g', 'w', 'a', 'c', 'e', 'u', '179', 'h', '4375', '4135', 'q', 'g']

Answer:
a, c, e, f, g, h, i, l, m, q, s, u, w, z