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: ['8253', 'R', '2411', '9699', '5447', 'C']

8253, 18, 2411, 9699, 5447, 3