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: ['T', '3813', '3545', 'l', 'O', '8871', '6887', 'u', '891', 'R', '1707', '3439', 'D', '3819']

20, 3813, 3545, 12, 15, 8871, 6887, 21, 891, 18, 1707, 3439, 4, 3819