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:
['p', '4329', '2437', '6279', 'u', '459', 'f', 'c', 'i', 'w', 'n', 't', '429', 'n', '73', '4995', 'p', 'z', '8459', '6133', 'y', 'r', '4057', 'a', '2717', '7803', 'r', 'm', '2879', '6989', '7223', 'v', '7929']
answer:
a, c, f, i, m, n, p, r, t, u, v, w, y, z


question:
['163', 'x', 'g', '5997', 'm', 'l', '7225', '7907', '375', 'y', 'a', 'j', 'c', 'j', '7755', '147', 'h', '3845', 'y', 's', 'h', 'u', '8737', '6091', 'j', 'f', 'c', '7395', '881', '1771', 'y', '3691', 'h']
answer:
a, c, f, g, h, j, l, m, s, u, x, y


question:
['u', 'd', '5037', '3095', '889', '6195', 'n', '345', '6055', '8209', 'd', '1753', '1945', 'v', '6303', 'y', 'p', '7125', '517', '8053', 't', '413', '4573', 'b', '9789', '2983', '6591', '2239', 's', '225', '1811', '6901', 'o', 'z', '5083', 'n', '4067', 's', '953', '3429', '8297', 'z', '9363']
answer:

b, d, n, o, p, s, t, u, v, y, z