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: ['s', 'w', '8949', '4025']

SOLUTION: s, w

PROBLEM: ['u', 'd', '4193', '5687', 'p', 'r', '7787', 't']

SOLUTION: d, p, r, t, u

PROBLEM: ['q', 'a', '8669', '7675', '777', '7315', 'e', '2227', 'o', 't', '681', '5529', 'j', 'h', 'g', 'r', '9801', 'z', 'e', '841', 'u', '2763', '401', '3787', 'k', 'o', '3453', '4195', 'x', '8329', '7297', 'k', 'p', 'r', '7603', 'l', '6737', '9641', '5395', '9169', '5725']

SOLUTION:
a, e, g, h, j, k, l, o, p, q, r, t, u, x, z