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: ['f', 'a', 'r', '4009', 'k', 'a', 'g', '7725', 'v', 'b', '6705', 'a', '6583', '3159', 'c', 'w', 'x', 'h', '7625', 'p', 'y', '5645', 'k', 'r', 'j', '4175', 'r', '3103', '8631', '5999', 'p', 'g', 'h']

SOLUTION: a, b, c, f, g, h, j, k, p, r, v, w, x, y

PROBLEM: ['2247', 'w', 'h', '4675', '6153', 'f', '6029', 'o', 'd', 'j', 'z', 'y', 'i', '6899', '3917', 'u', '6447', '6405', 'a', '1705', '8585', 'v', 'f', 'r']

SOLUTION: a, d, f, h, i, j, o, r, u, v, w, y, z

PROBLEM: ['7461', 'g', 'l', 'v', '4747', '4769', 'x', 'k', 'h', '7953', '1627', '5459', 'f', '3581', '6005', 'm', 'b', 'q', 'v', '9845', '7619', '9663', 'm', 'k', '7409', '1475', 'd', '2995', '7991', '4875', 'm', 'b', '4727', 'm', '4381', 'i', 'h', '4215', '9255', '3637', '4169', '3551', 'e']

SOLUTION:
b, d, e, f, g, h, i, k, l, m, q, v, x