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: ['y', '5271', '5973', '4739', 'U', '6291', 'U', '8207', '6227']

25, 5271, 5973, 4739, 21, 6291, 21, 8207, 6227