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: ['m', '7807', 'n', 'w', '5097', '1023', '2723', 'u', '3055', '7285', 'f', 'm', 'w', '5197', '9743', '7519', '4451', 'c', 't', '1939', '5847']

SOLUTION: c, f, m, n, t, u, w

PROBLEM: ['8741', 'h', '2147', '373', 'c', 'r', '2639', '3511', '1393', 't', '7173', 'f', '9371', '7659', 'q', '4799', 'f', '1967', '1905', '8783', 'i', 'n', 'z', '6395', 'u', 'i', '1493', '1395', '1909', '477', 'i', '8547', '393', '2203', '6893', 'y', '2085', '6445', '7753', '4027', 'h', 'y', '7963']

SOLUTION: c, f, h, i, n, q, r, t, u, y, z

PROBLEM: ['3515', 'k', '6947', 'c', 'j', 'j', '6089', '3941', '4809', 'y', '6165', '7441', '1331', '4055', 'w', 'p']

SOLUTION:
c, j, k, p, w, y