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: ['5161', 'v', 'y', '6005', 'y', 'l', '5451', 'z', 'j', 'd', '4597', '9319', '1241', 'g', 'f', 'b', 'g', '683', '763', 'm']

SOLUTION: b, d, f, g, j, l, m, v, y, z

PROBLEM: ['2527', '9123', '8717']

SOLUTION: -1

PROBLEM: ['6861', '9345', 's', 'x', 'g', '2027', '965', '3537', 'u', '1057', 'f', 't', '3693', '3915', '4571']

SOLUTION:
f, g, s, t, u, x