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: ['i', 'X', 'z', 'O', '9021', '4009', '8977', '1699', '7261', '4711', 't', 'E']

9, 24, 26, 15, 9021, 4009, 8977, 1699, 7261, 4711, 20, 5