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: ['2521', '8027', 'm', '193', '615', 'l', '1947', '5949', '6307', 'r', '1015', '743', 'v', '6949', 'b', 'g', '8841', 'c', 'b', '2879']

Answer: b, c, g, l, m, r, v


Question: ['7585', '4849', 'd', '6971', 'q', '9269', 'h', '3347', 'k', 'n', 'j', '6491', 'a', '3031', 'x', '3517', 'b', 'c', 'h', 'i', '1469', 't', '7451', 'b', 'u', '3419', 't', '3783', '3715', '2545', 'i', 'p', 'z', '441', 'f', '5335', '2495']

Answer:
a, b, c, d, f, h, i, j, k, n, p, q, t, u, x, z