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: ['8399', '3789', '4209', 'r', '891', '2175', 'z', 'a', '7031', 'E', 'o', 'I', 'e', '2815', 'T', '629', '509', '8339', 'J', '1583', 'a', '629', '6561', '9295', '3909', '2619', '5', '2999']

8399, 3789, 4209, 18, 891, 2175, 26, 1, 7031, 5, 15, 9, 5, 2815, 20, 629, 509, 8339, 10, 1583, 1, 629, 6561, 9295, 3909, 2619, 5, 2999