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: ['k', '1995', 'b', '2581', 'x', '2639', 'i', '6761', '2701', 'd', '6993', '9375', 'r', 'm', '249', '8115', '8179', 't', '4901', 'i', '6197', '2809', 'e', 's', 'j', '4261', 'f', '6649', '7527', '3839', '5651', '9287', 'n', '2505', 's', 'q', '2825', 'g']

SOLUTION: b, d, e, f, g, i, j, k, m, n, q, r, s, t, x

PROBLEM: ['2459', '3709', 'f', '8673', '9313', 'm', 'd', 'g', 'c', 'g', 'u', 'f', 'p', 'i', '8771', '3613', '9669', '6221', '1211', '8331', '2295', 'b', 'f', 'm', '1377', '9831', '1751', 'k', '4831', 'm', '2747', '3435', '4543', 'c', '1729', 'e', '7093', '397', 'm', '383', '2019']

SOLUTION: b, c, d, e, f, g, i, k, m, p, u

PROBLEM: ['y', '2391', '6431']

SOLUTION:
y