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: ['p', '3981', 'e', '5949', 'p', '4075', '1919', 'w', 'r', '8059', '4303', 'f', '5201', '2255', '2737', '7395', '8809', 'j', 'z', 'n', '4797']

SOLUTION: e, f, j, n, p, r, w, z

PROBLEM: ['6249', '1235']

SOLUTION: -1

PROBLEM: ['g', '1269', '1771', '8603', 'z', '3017', 'h', 'c', '6837', 't', 'f', '383', '5917', '8067', 'p', '5559', '913', '3363', '617', '8815', '7629', 'z', 'f', '8951', '3659', 'f', '3659', 'b', 'o', '691', '7593', 'j', 'j', 'j', 't']

SOLUTION:
b, c, f, g, h, j, o, p, t, z