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: ['r', 's', '3409', 'a', 'e', '6855', 'i', 'n', '8655', 's', 't', '8401', 'u', '9603', '8815', 'q', 'a', 'x', 'i', '8455', 'e', '5877', '3917', 'p']

SOLUTION: a, e, i, n, p, q, r, s, t, u, x

PROBLEM: ['8357', 'x', 'w', '287', 'z', '2733', '1757', 'w', 'g', '1393', '7201', '4931', 'k', '5185', 'x', '6313', '2255', 'z', 'v', '3593', '6191', '4423', 'm', 'k', '3209', '3559', 'c', 'n', 'm', '5461', '2997', '235', '4045', '6597', 'v', 'e', 'p', 'c', 'k', 'd', '5529', '6241', 'u', 'f', '8067']

SOLUTION: c, d, e, f, g, k, m, n, p, u, v, w, x, z

PROBLEM: ['7489', '9853', 'j', '4827', 'm', 'c', '1433', 'i', 't', '4057', 'k', '3429', 'w', '8027', '465', '1335', '4689', 'g', '6879', '8249', 'w', 'g', '3115', '1111', '4171', 't', 'p', 'g', 'f']

SOLUTION:
c, f, g, i, j, k, m, p, t, w