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: ['D', '8201', 'o', 'O', 'a', 'a', '2475', 'k', '3099', '9789', 'f', 'i', 'k', 'H', 'f', 'Q', 'L', 'D', '3857', '645', 'g']

4, 8201, 15, 15, 1, 1, 2475, 11, 3099, 9789, 6, 9, 11, 8, 6, 17, 12, 4, 3857, 645, 7