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: ['L', '6073', 'o', 'J', 't', '911', '2949', 'x', '2273', 'O', 'l', '9955', 'E']

12, 6073, 15, 10, 20, 911, 2949, 24, 2273, 15, 12, 9955, 5