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: ['2903', '4507', 's', '9515', 'G', 'T', '9621', 't', '345', 'r', 'm', 'i', 'E']

2903, 4507, 19, 9515, 7, 20, 9621, 20, 345, 18, 13, 9, 5