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', 'a', 'M', '939', '8953', 'c', 'F', '9963', 'D', 'h', 'I', '4715', '9879', '4689', 'Z', 'M', 'p', '5983', '1475', 'G']

15, 1, 13, 939, 8953, 3, 6, 9963, 4, 8, 9, 4715, 9879, 4689, 26, 13, 16, 5983, 1475, 7