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: ['O', 'p', '887', '149', 'g', 'f', 'l', '6053', '5409', '4649', 'E', 'm', '5993', '3275', '4687', 'T', '9461', '4225', '4141']

15, 16, 887, 149, 7, 6, 12, 6053, 5409, 4649, 5, 13, 5993, 3275, 4687, 20, 9461, 4225, 4141