TASK DEFINITION: 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.
PROBLEM: ['7071', 'h', '837', 'z', 'c', '2217', 'c', '6341', '6607', 'g', '3569', 'a', 'h', 't', 'b', 'f', 'g', 'f', 'l', 'b', 'x', 'o', 'r', '8949', '8071', '1507', 'v']

SOLUTION: a, b, c, f, g, h, l, o, r, t, v, x, z

PROBLEM: ['w', '1367', '5389', '9515']

SOLUTION: w

PROBLEM: ['5093', 'x', '5573', '3995', '1827', 'e', 'n', '129', 'n', '867', '7961', '7957', '3127', '5989', 'h', 'm']

SOLUTION:
e, h, m, n, x