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: ['4637', 'f', '2639', '8623', 'w', 'e', 'k', '5503', 'x', '6633', '7553', '1455', 'u', '1773', 'r', 'u', '1489', 'u', '1303', '9683', 'z', '565', '7041', 'x', 'z', '9431', 'k', 'v', 'j', 'z', '5469', '5665', '4089', '4951', '8263', '5675', '4095', '7745', 'z', '2437', 'd', 'e', 'w']

SOLUTION: d, e, f, j, k, r, u, v, w, x, z

PROBLEM: ['5957', 'd', 'i', 'b', 'e', '5565', 'c', 'i', '2919']

SOLUTION: b, c, d, e, i

PROBLEM: ['r', '5909', 'h', 'e', 'r', '1987', '1159', 'l', '3211', 'j', 'n', '3821', '9537', '9217', '3625', 'e', '2927', 'm', 's', '4813', '5563', '7501', 'z', '6763', 'e', 'z', '3345', '7423', '453', '1151', 'o', '1103', '5505', 'r', 'c']

SOLUTION:
c, e, h, j, l, m, n, o, r, s, z