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', '9015', '3639', 'y', 'S', 'p', 'P', '9987', 'd', 'R', 'y', 'P', '1983', 't', '1701', 'K', '2609', '6561', 'm']

15, 9015, 3639, 25, 19, 16, 16, 9987, 4, 18, 25, 16, 1983, 20, 1701, 11, 2609, 6561, 13