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: ['l', 'g', 'd', 'p', '8163', '6643', 'o', 'p', 'm']

SOLUTION: d, g, l, m, o, p

PROBLEM: ['h', 'v', '1263', 'y', '3299', 'd', 'a', 'h', 's', '2007', '7597', '1015', 'k', '6643', '6959', 'g', 'u', 'd', '5737', 'n', 'z', 'y', 'b', 'g', '9059', '7349', 'j', 'w', 'i', 'z', 'p', '5809', 'x', '4421', 'g', '6399', '3965']

SOLUTION: a, b, d, g, h, i, j, k, n, p, s, u, v, w, x, y, z

PROBLEM: ['s', 'j', 'c', '725', 'g', '5111', 'v', 'c', '2955', '6073', 'i', '3561', 'm', 'w', '5075', '7855', '1297', 'w', 'j', 'm', '915', 'm', 't', '3245']

SOLUTION:
c, g, i, j, m, s, t, v, w