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: ['t', 'P', 'l', '4791', 'X', '9993', '4823', 'g', '4345', 'X', '9553', 'l', '4013']

20, 16, 12, 4791, 24, 9993, 4823, 7, 4345, 24, 9553, 12, 4013