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: ['t', 'c', 'r', '4459', 'o', '1407', 'x', '1515', '331', 'm', '1535', 'p', 'u', 'g', '2513', 'o', '7827', '8149', 'd', 'z', 'q', '5655', 'x', '9997', '2809', 'g', 'h', '6309', 'a', 'j', '9773', '2115', 't', '9113', 'q', 'o', '427', 's', '3815', '5423', 's', 'n', 'i', 'o', '3643']

SOLUTION: a, c, d, g, h, i, j, m, n, o, p, q, r, s, t, u, x, z

PROBLEM: ['g', 'x', 'l', 'e', 'd', '1345', '1763', 'm', 'c', '2057', 's', 'a', '4127', 'y', 'h', '8581', 'o', '9203', '4761', 'd', 'u', 'n']

SOLUTION: a, c, d, e, g, h, l, m, n, o, s, u, x, y

PROBLEM: ['a', '9215', 'w', '6451', 'a', 'e', '8213', '6337', 'a', '6231', 'p', 't', 't', '6307', '6109', 'r', '3407', 'g', '1821', 'z', 'y', '4301', '7459', '6103', '5505', '4159', 't', 'u', 'a', '8107']

SOLUTION:
a, e, g, p, r, t, u, w, y, z