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', '4243', '8209', 'r', '6785', '4485', '8635', '2153', '8571', '7563', 'm', 'g', 'i', 'Y', '1567']

15, 4243, 8209, 18, 6785, 4485, 8635, 2153, 8571, 7563, 13, 7, 9, 25, 1567