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: ['3651', 'c', 'm', '7123', '2981', '9649', 'o', '2181', 'h', '8577', 'a', '5027', 'x', 'u', '1039', '347', '8219', 'c', '1063', '8885', 'f', 'd', '3067', '2509', 'i', 's', '5509', '2003', 'h', '8869', 'x', 'd', '5141', 'h', 'i', 'b', 'o']

SOLUTION: a, b, c, d, f, h, i, m, o, s, u, x

PROBLEM: ['1657', 'u', '1849', '425', 'v', '6435', 'j', '2985', '921', '9553', '2621', 'i', '7103', 'd', '8563', 'l', 'b', '6727', '4235', 'n', '8021', 'd', 'z', '437', 'm', '5695', 't', '3421', 'e', 'a', '2941', '791', '1417', '9247', 'h']

SOLUTION: a, b, d, e, h, i, j, l, m, n, t, u, v, z

PROBLEM: ['p', '6529', '8775', '8629', '7793']

SOLUTION:
p