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: ['7561', 'r', '3419', 'k', 's', '5997', 'u', '6635', '7003', '8491', 'i', '9835', 'c', '8827', 'h', 'a', 'j', '7675', '1995', '1223']

SOLUTION: a, c, h, i, j, k, r, s, u

PROBLEM: ['8051', 'h', 'g', 's', 't', 'p', 'w', 'x', 's', '8521', 'm', '9719', 'j', 'n', 'i']

SOLUTION: g, h, i, j, m, n, p, s, t, w, x

PROBLEM: ['f', 'm', 'x', 'g', '9267', 's', '1611', '4793', 'a', '9063', 'o', '9589', 'd', 'q', 'p', '5641', '3743', '3077', '245', '9919', 'm', '1537', 'v']

SOLUTION:
a, d, f, g, m, o, p, q, s, v, x