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: ['1799', '6409', '9257', '5923', 'm', 'j', '2565', '715']

Answer: j, m


Question: ['j', 'a', 'z', 'h', '4129', '4159', 'm', 'o', 'o', '1193', '2905', '3083', 'q', 't', 'm', 'o', '673', '7547', 'n', 'c', 'r', 't', '2897', '4959', 'z', '2377', 'y', '7977', 'u', 'b', 's', 'w', 'e', 'd', '8051']

Answer: a, b, c, d, e, h, j, m, n, o, q, r, s, t, u, w, y, z


Question: ['7257', 'n', '1455', 'g', 'm', 'a', '8279', '1997', '8701', 'u', '877', 'v', 'r', '6593', 'q', '355', 'e', '3905', 'c', 'p', '8801', 'r', '6059', 'd', 'l', '815', 'w', '7971', 'a', '4451', '3175', '5967', 't', '6299', 'k', '4615', 'n', '7255', 't', '5361', '2797', 'v', '4483', '3821']

Answer:
a, c, d, e, g, k, l, m, n, p, q, r, t, u, v, w