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: ['3103', 'Y', 'V', '1949', 'u', '6369', 'G', '6729', '19']

3103, 25, 22, 1949, 21, 6369, 7, 6729, 19