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: ['S', 't', '8707', '7493', 'Y', 's', 'j', '5871', '4427', 'c', 'D', '889']

19, 20, 8707, 7493, 25, 19, 10, 5871, 4427, 3, 4, 889