Definition: In this task, you are given an input list A. You need to convert all the alphabets in the list with a number representing their position in the English alphabet. E.g., replace A by 1, B by 2, a by 1, b by 2, and so on.
Input: ['u', 'i', '2399', 'W', '8809', 'x', '2507', 'D', '7887', '4475', 'F', 'n', 'N', 'I', 'W', '3861', '5975', 'b', 'M', 'l', 'p', '9319', 'P', 'G', '8475', '2495', '3687', 'W', 'c']

21, 9, 2399, 23, 8809, 24, 2507, 4, 7887, 4475, 6, 14, 14, 9, 23, 3861, 5975, 2, 13, 12, 16, 9319, 16, 7, 8475, 2495, 3687, 23, 3